Noticed that making a field visible/hidden while editing will not let you save until you first go back and save your project edits. The "Save" button for the fields view is grayed out. It does not prompt to tell you this, you just have to figure it out. It seems like a fairly common workflow to hide a field, even while editing. ArcPro 2.2.2
I believe the outstanding edits need to be saved first in order to apply the schema change. It's just the AGP workflow as it were.