Receiving an error that there is no function user on SAIL forms. Please advise

I have tried both fn!user() and user(). The function exists, and you can use it normally in an expression rule. It just doesn't work when called as the function parameter of the apply function.

I have tried both fn!user() and user(). The function exists, and you can use it normally in an expression rule. It just doesn't work when called as the function parameter of the apply function.