After buying OnePlus One - Google Keep stopped syncing "Sync is currently experiencing problems. It will be back shortly. " I bought OnePlus One. Keep did not sync any cards. I thought it was problem with the phone but than I uninstalled and installed Keep on my tablet and it stopped working with it too. 

 
I get this in my sync screen in OnePlus One (left) / Nexus 7 Android 5 (right).

Notice the Sync is experiencing problems below. 

When I try to play music on google play music app it stops immediately after start. Keep not syncing. My friend does not have this problem so it does not seem to be global.

It seems as if I broken my account somehow. Can I do anything about this? I have no clue who could help me resolve this.

Here is a video were I show the behavior Google Keep does not sync. Please help: http://youtu.be/AbAU-8TIf_w
Ok, so I found the solution with help from Psychol3oy on OnePlus One Jira. The issue is on Google site. They do not respond to any attempts to contact them, so I managed to find the issue myself.

Psychol3oy suggested on this ticket in OPO Jira, to turn on developer options on your device like this: 


Enter settings on android
About phone
Tap on build number numerous times - it will say you enabled developer options. 
Go back to settings and enter developer options
This will vary from device to device. I had to enable "Android debugging" and "Power menu bug reports"
Go to settings
Find Google in Accounts
Attempt to synchronize Keep
In OnePlus One hold power button and press bug report
It will slowly generate a bug report for you. Share it with you via email, or any other way.
Investigate. I am not sure how Android developers look for it, I just looked for "keep" and "sync" keywords within the log.


I found in mine there was some issue with one of the cards I had on my Keep. It looked like this:

01-12 21:39:04.993 1562 16531 E SyncScheduler: Ignoring sync request: rate limited 

(on connection limit)
01-12 21:39:05.003 16099 16529 V KeepSync: Connected to GoogleApiClient.
01-12 21:39:08.653 16099 16529 I KeepSync: documents to pin: 5 Documents to unpin: 0
01-12 21:39:08.793 16099 16529 E SQLiteDatabase: Error inserting user_edited_timestamp=1418138554492 time_created=1418138472081 notification_state=0 type=0 is_new_list_item_from_top=0 title=Marian Simonovi realtime_data_server_version=2 has_read=1 last_modifier_email=null parent_id=0 server_id=1RV2lPCgF9kzIYEAXKFxpH1JOxAsDRredxIoFvBrOiHaB2vYiLRFqoB3FISCS11A account_id=1 order_in_parent=116391936 color_name=GREEN time_last_updated=1418200125436 base_version=29 last_changes_seen_timestamp=1418140253433 is_archived=0 is_graveyard_closed=0 is_trashed=0 is_deleted=0 is_owner=0 sharer_email=null is_dirty=0 uuid=1418138472079.1701639728 is_graveyard_off=0
01-12 21:39:08.793 16099 16529 E SQLiteDatabase: android.database.sqlite.SQLiteConstraintException: columns account_id, uuid are not unique (code 19)
01-12 21:39:08.793 16099 16529 E SQLiteDatabase: at android.database.sqlite.SQLiteConnection.nativeExecuteForLastInsertedRowId(Native Method)
01-12 21:39:08.793 16099 16529 E SQLiteDatabase: at android.database.sqlite.SQLiteConnection.executeForLastInsertedRowId(SQLiteConnection.java:782)
01-12 21:39:08.793 16099 16529 E SQLiteDatabase: at android.database.sqlite.SQLiteSession.executeForLastInsertedRowId(SQLiteSession.java:788)
01-12 21:39:08.793 16099 16529 E SQLiteDatabase: at android.database.sqlite.SQLiteStatement.executeInsert(SQLiteStatement.java:86)
01-12 21:39:08.793 16099 16529 E SQLiteDatabase: at android.database.sqlite.SQLiteDatabase.insertWithOnConflict(SQLiteDatabase.java:1469)
01-12 21:39:08.793 16099 16529 E SQLiteDatabase: at android.database.sqlite.SQLiteDatabase.insert(SQLiteDatabase.java:1339)
01-12 21:39:08.793 16099 16529 E SQLiteDatabase: at com.google.android.keep.provider.KeepProvider.a(SourceFile:1762)
01-12 21:39:08.793 16099 16529 E SQLiteDatabase: at com.google.android.keep.provider.KeepProvider.insertInTransaction(SourceFile:1650)
01-12 21:39:08.793 16099 16529 E SQLiteDatabase: at com.android.common.content.SQLiteContentProvider.insert(SourceFile:113)
01-12 21:39:08.793 16099 16529 E SQLiteDatabase: at android.content.ContentProviderOperation.apply(ContentProviderOperation.java:214)
01-12 21:39:08.793 16099 16529 E SQLiteDatabase: at com.android.common.content.SQLiteContentProvider.applyBatch(SourceFile:231)
01-12 21:39:08.793 16099 16529 E SQLiteDatabase: at com.google.android.keep.provider.KeepProvider.applyBatch(SourceFile:1633)
01-12 21:39:08.793 16099 16529 E SQLiteDatabase: at android.content.ContentProvider$Transport.applyBatch(ContentProvider.java:260)
01-12 21:39:08.793 16099 16529 E SQLiteDatabase: at android.content.ContentProviderClient.applyBatch(ContentProviderClient.java:377)
01-12 21:39:08.793 16099 16529 E SQLiteDatabase: at android.content.ContentResolver.applyBatch(ContentResolver.java:1227)
01-12 21:39:08.793 16099 16529 E SQLiteDatabase: at com.google.android.keep.syncadapter.DownSyncResponseProcessor.lZ(SourceFile:295)
01-12 21:39:08.793 16099 16529 E SQLiteDatabase: at com.google.android.keep.syncadapter.DownSyncResponseProcessor.q(SourceFile:263)
01-12 21:39:08.793 16099 16529 E SQLiteDatabase: at com.google.android.keep.syncadapter.DownSyncResponseProcessor.lY(SourceFile:236)
01-12 21:39:08.793 16099 16529 E SQLiteDatabase: at com.google.android.keep.syncadapter.KeepSyncAdapter.a(SourceFile:311)
01-12 21:39:08.793 16099 16529 E SQLiteDatabase: at com.google.android.keep.syncadapter.KeepSyncAdapter.onPerformSync(SourceFile:198)
01-12 21:39:08.793 16099 16529 E SQLiteDatabase: at android.content.AbstractThreadedSyncAdapter$SyncThread.run(AbstractThreadedSyncAdapter.java:259)
01-12 21:39:08.793 16099 16529 E Keep : Failed to insert row for content://com.google.android.keep/tree_entity?caller_is_syncadapter=true
01-12 21:39:08.813 16099 16529 E KeepSync: OperationApplicationException error while applying sync results
01-12 21:39:08.813 16099 16529 W KeepSync: Sync result 3
01-12 21:39:08.853 16099 16099 D WearableClient: WearableClientImpl.onPostInitHandler: done
01-12 21:39:08.903 798 851 D SyncManager: failed sync operation mimkorn@gmail.com u0 (com.google), com.google.android.keep, SERVER, latestRunTime 3728633, reason: 10013, SyncResult: stats [ numParseExceptions: 1]
01-12 21:39:08.903 798 851 D SyncManager: not retrying sync operation because the error is a hard error: mimkorn@gmail.com u0 (com.google), com.google.android.keep, SERVER, latestRunTime 3856031, reason: 10013


Pay attention to the longest row, saying: 

01-12 21:39:08.793 16099 16529 E SQLiteDatabase: Error inserting user_edited_timestamp=1418138554492 time_created=1418138472081 notification_state=0 type=0 is_new_list_item_from_top=0 title=Marian Simonovi realtime_data_server_version=2 has_read=1 last_modifier_email=null parent_id=0 server_id=1RV2lPCgF9kzIYEAXKFxpH1JOxAsDRredxIoFvBrOiHaB2vYiLRFqoB3FISCS11A account_id=1 order_in_parent=116391936 color_name=GREEN time_last_updated=1418200125436 base_version=29 last_changes_seen_timestamp=1418140253433 is_archived=0 is_graveyard_closed=0 is_trashed=0 is_deleted=0 is_owner=0 sharer_email=null is_dirty=0 uuid=1418138472079.1701639728 is_graveyard_off=0


The title parameter on this row is saying the card name "Marian Simonovi". I found this card. It was a card shared by a friend with me. 


I deleted (not archived, but deleted) this card on web interface of Keep.
I tried to sync my device and it worked immediately.


I know this is rather more difficult to do and it might not be this easy on your non-OPO device. You might have difficulties get to logs on your device (might have to use Android Studio on your PC). But this is what worked for me. Hope your issue will be similar.

This seems to be a bug on Google site. If you know a way how to let them know other than the ways I alredy tried (contacted developers via Google play, sent bug report, wrote google groups question, wrote on xda-forums) please let me, or them know about this.