I recall having some problems with the NextCloud sync client, which I got round by installing Nextcloud Dev from F-Droid instead. It’s the beta / developer version of the official Nextcloud Android app, and the F-droid page says
Do not install this version for your productive work!
Intended for users willing to test new features and report bugs if they occur.
But it has worked fine: so well that I had forgotten that I’m not using the stable version!