Attributes lists in the Attributes editor are not scrollable (and no scrollbar appears) even if the list control is focused via mouse or keyboard, until either of these two things happen:
Mouse: the bottom partially-visible item is clicked with a mouse (because clicking any fully-visible item or using the scrollwheel doesn't make the list scrollable).
Keyboard: tabbing via keyboard to set focus doesn't make it scrollable until one of the cursor keys is pressed.
It would be ideal if the enabled attributes lists could be scrollable (e.g., via a scrollwheel when moused over a list) even when the list controls are not focused so that the users can put the attribute of interest into view before clicking it.
This does still seem to be a problem in V12.4.4 (after reboot).
Highlight a file, then run SetAttr, then tick 'Change Attributes'.
There is no runner on the little box, and the last two items are hidden.
3A. Click on a visible attribute, press the down-arrow, and the runner appears (but you then have to click off the attribute that you have just clicked on).
3B. Alternatively, start again and click on the almost-hidden attribute at the bottom, and the runner appears without using the down-arrow.