Getting HTTP 400

[wolverinechris]

I'm new to Home Assistant but have been muddling through it. I was getting HTTP 401's before I got the long-live token working, so at least auth seems good. Now I'm getting HTTP 400s.

I wondered if it might be something to do with known_devices.yaml. It seems to be getting deprecated per https://community.home-assistant.io/t/no-known-devices-yaml-file/138416 . Working on a fresh Home Assistant install, this file was not created, so I tried manually uploading one (containing just the contents provided by FindMySync), using the File Editor Add-On. It didn't seem to make any difference.

I'm sort of at a loss for what to do next. I suppose my main option would be to manually edit the code I guess...honestly an option to output this to a log file or CSV would be really handy for those of us without Home Assistant setups.