If I'm in the middle of an editing session and want to try to force a table custom sort to re-apply without leaving the editing session, the custom sort GUI does not allow me to do that unless I make a change to the existing custom sort, apply that, and then revert back to the custom sort I really want and apply that. The "OK" button remains grayed out until a change to the sort order is made, and making a change without applying it and then reverting back to the original sort order returns the OK button to grayed out status, so I can't even trick it. This is true even if I make a manual save during the edit session to lock in the new values.
OK button grayed out in Custom Sort
My workaround trick for now is to add an additional sort field in the last sorting position that has no actual impact on the sorting order (either because all its values are the same or are all empty or all other sort fields already establish a unique sorting order) and flip that bogus field between Ascending and Descending as a fake "change".
Is the inability to re-apply a custom sort after an edit expected behavior? Would be nice not to have to do my little clunky workaround.
I've found some oddities with sorting (I think one was even logged as a bug) that was temporarily "fixed" by closing and reopening the attribute table. May not be the best workflow, even if it works, but it's an idea.