Does anyone know what causes this and how to fix it?

when I get an error like this I usually open a support case and they look at what the error is behind the scenes

Thanks. I tried and they said it wasnt critical / system down 😞 and it might be a browser issue. We dont pay for advanced support. I cleared my cache, etc but still an issue.

😕 have you tried chrome or brave to test their theory?

yeah. chrome, firefox, and edge. Going to try safari on my wifes computer when she gets home. It's on custom fields that do have help defined, so we will see what they say.