Thank you for the response. By 'new' architecture you mean the crappy Win32 application that you bridged to work on PCs. What you seem to forget is that there are other W10 devices out there that are not a PC. Besides, do you honestly expect your customers to pay twice for an app just because you decided that you cannot manage UWP development and had therefore to go back to Win32?
It seems that synchronising the data does no longer work when using the application on different platforms and storing the data on OneDrive. I can change data on any device, however, the changes do not show on a device running on a different platform. Synchronisation between iOS devices seems to work, likewise the data on W10 devices shows as expected. The iOS app version is 6.0.6 (234), the W10 app version is 5.5.7.