I tried to reproduce the issue but I can’t.
Added some notes on my webapp - the sync to outlook 2016 with active sync works fine.
Kopano-Core - 8.5.5 and Outlook 2016 MSO - 16.0.9029.2106 32 BIT
and after my update which I just made: 16.0.9029.2253 32 BIT - it still works (-:
Z-Push Version: 2.4.0+0-0
which one are u using?
Maybe you can add another outlook profile on the outlook 2013 computer and verify if it works there with active sync?