GetUser($layer).username Not Working ONLINE

[LeviCecil]

I'm trying to calculate full user names in a Field Maps form for an AGOL map. The GetUser($layer).username function works in the Arcade editor in Field Maps designer (prints "Levi Cecil" as opposed to my username "lcecil5") but this data doesn't write to the attribute table. It's just null. I've seen a lot of posts about how this function doesn't work offline, but I'm strictly online. 

[JustinReynolds]

I'm having a similar issue all of the sudden.  GetUser no longer has required parameters (i.e. GetUser().username should work).  

I have no issues with GetUser().username in the arcade editor in AGOL, it returns the active user in the active portal. But in Map Viewer and in Field Maps I get errors about or similar to a null object not having an attribute named 'username'.  This is in AGOL, but on a proxied service with stored credentials whose data source is in Enterprise 10.9.1.  This could be the problem, but I haven't tested further at this point.

[LeviCecil]

Well, I just got it to work sort of. I set the field to "required" and "visible" in the Field Maps and my name showed up in the field in the Field Maps form. I'm working on webhooks email notifications in Make at the moment, and the output is weird. It has [Collection] before my name. WTF??

Logged by user: [Collection]Levi Cecil