Same here with 3.7.1 . and WebDav.
I checked with another phones, it is related to 3.7.1 and not iOS 14.
Using an iOS shortcut with x-callback doesn't work either.
I'm looking into these issues and hope to have a fix ASAP.
How do you get 3.7.2?
3.7.2 will be rolling out over the next week if you use automatic update of your apps. You can however choose to install it now by going to the updates section in the App Store app (e.g. long press on the App Store icon and choose updates, then scroll down to see beorg and tap Update).