I have had a look in the Known Differences and Issues thread and couldn't see what I describe below. I have tested it with two rulesets (PFRPG2 and 5E) and behaviour is the same, so it doesn't appear to be a ruleset bug.

When you modify a field which allows a temporary modifier (little icon in top-right corner of field) using CRTL + Mouse-wheel, the main number is modified correctly, but the small top-right bubble to indicate the modification doesn't update to reflect the change until you reload the campaign from the launcher (/reload doesn't work).

This occurs when modifying a value up and down, and in at the very least both PFRPG2 and 5E.