Hi @Nicole_Ueberschär , just a little bit after making my first post, we figured out how to get it to work. Turns out that the getUser() function was somehow causing the issue (even though the Test would work). After tweaking the function a bit, it now works. See below.
var port = Portal('https://xxxx.com/portal');
var fs = FeatureSetByPortalItem(
port,
'xxxxxxxxxxxxxxxxxx',
0,
[
'Inspector'
],
false
);
Console(Count(fs)) // to get number of features in feature service in Console
var u = getUser(port);
var fullName = u.username;
Console (fullname) // to check in the Console that the fullname is returned
var filfs = Filter(fs, `Inspector= '${fullname}'`) // change field as needed
Console(Count(filfs)) // check in Console that it is returning the correct number of features assigned to the user
return filfs