I noticed that if I start the game from the Banished shortcut, my cursor won't move, but when I launch the game from the GOG Galaxy, it works fine. Also when I launch with Banished shortcut, it reverts back to DX 10 or something. That might be the cause. But in any case no problems lauching with Galaxy first.
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Edit...
Ok, the cursor is working, it just becomes invisible. I can still see which buttons light up when I'm lucky to hover over one.

Yep, once in a while the game settings for some unknown reason revert back to DirectX 9.0c. I have to change it back to DX11 to get the "invisible" cursor visible again.

So then why does it revert to DX9?
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Edit...
Okay, so if you have this cursor issue and the constant reverting to DX9, then I found the launcher that starts with the options to change to DX11 prior to playing.
c:\Program Files (x86)\GOG Galaxy\Games\Banished
Find and create shortcut for "Application-x64.exe".