Assuming the settings page still is giving you an error, but you are able to verify the token with that curl command at the same time, the only other thing I can think of would be if certain individual API calls were having an issue. Maybe double/triple check your API token permissions? Maybe one of the permissions it needs was removed or edited. You need exactly these permissions:
View attachment 324896
Anything missing or anything with the wrong permission (like Read instead of Edit) will be problems.
Yeah, everything is exactly like that.

