So @Beth and I were working through something similar in another post from @Amit (pardon me while I figure out how to link to that in a subsequent edit - UPDATED!). Also worth noting, I’m stuck at LTS8.2 so my limitations may be different than current release.
I can pick any user from the User Table (either via interactive table selection, or single select populated with the list of all users (just realized this was a thing at Office Hours) and use this to set a record placeholder in the user table.
When I specify either the Logged-in User or another specific user in the Trigger editor, I can see all of the User Profile + User Custom Fields are exposed:
But when I try to leverage the User Table record placeholder, I can only see a subset of the total user data (i…e. Name, Email, Phone Number, and Role are absent):
I think the same is true for Expression Editor.