Hmm how odd, I generated that one to specifically test this and I got the results I mentioned above, however I just disconnected that one (thus invalidating it) and created a new one and the endpoints are working as expected, including V5.
So, i’m not sure if there is a intermittent issue but I am seeing all expected results using OAUTH, so that may be the issue with @LiraNuna - invalidate the current OAUTH and try again - that endpoint is now working for me.