Can you post a screenshot of your Settings -> Storage page from both the Android Tablet and the Windows 10 installation? The storage page looks like this:
No active ‘show hidden tracks’, only one core, identical numbers in Overview - the only common denominator I can think of is that all the tracks were edited in various ways, album name change and/or Single status and/or new image and/or artist name change.
The common denominator mentioned in the last post isn’t strictly true, I’m now finding albums missing which were not edited in any way. 1.6 is simply failing to find certain music, but only on the W10 iterations of the controller.
Great news! It sounds like the Windows remotes aren’t set to view hidden albums. This setting is done per remote device, so even if it’s set to Yes on Android it may not be set on the Windows machines.
So if you go to one of the Windows machines and navigate to Settings > General and change the Show Hidden Tracks & Albums to Yes are you now able to see the missing media?