Nextcloud App keeps downloading files - but it shouldn't


I use Nextcloud App Version 2.6.2stable-Win64 (build 20191224) to backup files from my computer to an external server. This has worked fine for a couple of months, but recently I keep getting more and more messages telling me that files were downloaded from the server and renamed “… conflicted copy…” - but I never told the app to download anything!

Furthermore, there are subdirectories in my backup directory that the Nextcloud app doesn’t backup at all.

Any ideas how I can fix this? Do you need any more information to be able to help me? (plus: Is this the correct forum category at all?)

Thanks so much in advance!