I have a view generated from webform submissions. Two fields' output is being rewritten as follows
[value_1] (Sat. 11:00am)
[ value_2] (Sun. 2:00pm)

Value 2 is empty for some records, but '(Sun. 2:00pm)' still appears in the view all by itself despite both "Hide if empty"and "Hide rewriting if empty" are checked. This results in the following output:

Record 1
Reduce Wildfire Hazard (Saturday 11:00am)
Bio-regional Planning (Sun. 2:00pm)

Record 2
Reduce Wildfire Hazard (Saturday 11:00am)
(Sun. 2:00pm)

Any thoughts on why this is happening or how to fix it?

Comments

I did a very quick test and if the Display format of the webform submission value is HTML then it appears but if plain text then it doesn't, so something is included regardless of if empty when HTML is selected meaning the View doesn't see it as empty.

The example you have given suggests plain text should be ok.  You can add styling using the standard VIew Style settings or in the re-write, rather than the Webform Value settings.