Sync not working, config is lost

I’m seeing a problem with sync on my phone. It looked as if everything was migrated successfully, but when I tried to look at a document it sat forever trying to download it.

So I checked the sync setup, and no sync locations were listed. If I add one, it throws it away and takes me back to the sync locations screen and shows none set up. Log is empty.

It’s all working fine on my iPad, so I’m pretty sure it’s a bug. Wondering what I can do to diagnose?

Obviously I could zap all data from DTTG 4 on the iPhone and set it up again from scratch, but I’d rather help you find the bug and not have to do that.

I tried restarting the phone. DTTG version is 4.0 (18072), iOS is 26.1, phone is iPhone 16 Pro. Phone has 58GB of space so it shouldn’t be a space issue.

Edit: Just emailed support too.

The outcome was: I tried adding the WebDAV servers a few more times, it would say “location connected” but then give me a blank list of locations. Eventually after a few tries one of them worked, and then the other worked. So I’m up and running again, but it’s all a bit mysterious. The iPad had just migrated the connections from DTTG 3 without my having to do anything.