Sync should work with a Master Password as long as all Sync connected devices are using the same Master Password. Won't work with devices that don't use a Master Password and another "with" or with a different Master Password.

And you need to be careful when disabling the Master Password, at least on "desktop" devices, I believe all the Passwords might get deleted if that is done, or so I have read about stopping use of the Master Password; don't use a "mobile" device and don't know if that holds true there.

Thank you for the quick response :)

Both devices (android mobile and desktop) are using same master password.

Still they are not syncing!

Mobile has passwords, desktop is not able to sync from mobile.

I am going to move this thread over to the Firefox for Android queue. Maybe someone on that side of this fora would know more about this issue.

I have a similar problem on Windows. Android and desktop use the same master password Bookmarks sync fine, passwords do not.