I tested this now on my Edge 520 with iPhone X as well as with Huawei Mate 20 Pro, I get the same Error on both devices.
update.
I had a chat with Garmin online, I was told that Huawei has known issues, I tried to explain that it worked 100% for months, also on the iPhone. Referred me to dial a number in the UK. Interesting is that my Garmin 935 is still working fine, after the latest upgrade.