Android Backup manager - restore from Nougat to Marshmallow Earlier Device: LG Nexus 5X.
My Device: OnePlus 3

Earlier, I was able to use Tap&amp;Go or just import all the data by signing into my Google Acc.
However, with my device, when I used Tap&amp;Go or Google account sign-in (tried few hard resets), I was not able to choose my earlier device 
get data from. Only my old Galaxy Nexus was shown.
This resulted in phone not being setup, apps not being automatically installed or have the data restored...
I had to install apps manually however my data was not restored.

As it always worked well, I guess the issue might be with my earlier device running a newer version of android than my device (Nougat vs Marshmallow).   Or that some services are missing?

Anyone got into the same situation and can help?

I have tried restoring using adb bmgr, but it resulted in device not visible as well. Nexus 5x sees all 3 devices while OP3 sees just the 2.

shell@OnePlus3:/ $ bmgr list sets

33dbec2b8d69e175 : ONEPLUS A3003

3bcd9da5b052e84e : Galaxy Nexus




bullhead:/ $ bmgr list sets

34d36f59351444be : PiTRiS - Nexus 5x

33dbec2b8d69e175 : ONEPLUS A3003

3bcd9da5b052e84e : Galaxy Nexus


Any chance this is an issue with nougat, that it can't restore to Marshmallow? Or any other way how to force restore from 5X?
Thanks
For reference: One way is to use Titanium Backup app on older phone and then just restore the app's data on newer phone after transferring the backup data. The same thing could be accomplished using adb from your home computer, but you'd have to backup each app's data separately.

see this thread for more:
How to backup an Android device?