Did the Change Tracking internals change from SQL Server 2008 to 2012?
One doesn’t use the min_valid_version to track the changes. This is only used to validate if your client has to be reinitialized, if the metadata has been cleaned up before client could consume the changes. 

CHANGE_TRACKING_MIN_VALID_VERSION (Transact-SQL)

Obtains the minimum version that is valid for use in obtaining change tracking information from the specified table when you are using the CHANGETABLE function.

Min_valid_version changes with the cleanup version and doesn’t depend on the changes to the user table. Every time cleanup thread runs there could be an update to min_valid_version irrespective of data changes.

Previous to 2012, min_valid_version was marked same as cleanup version, when in fact it should be one more than the cleanup version as metadata for that version has already been cleaned up. In 2012 that is what they changed to make sure they update the right min_valid_version.

One should not be tracking change using min_valid_version, instead should be saving the last_sync_version after every sync and call the CHANGETABLE to enumerate the changes after the last sync version.

By design - Min valid version changes with the cleanup version and doesn’t depend on the changes to the user table. Every time cleanup thread runs there could be an update to min valid version irrespective of data changes. 

Resolve - Change procedure to use 'current_version' instead of 'min_valid_version'