Cannot nudge clips on timeline

I am using Premiere Elements 2021 on a Mac (with Catalina).  I am trying to sync up a bunch of clips on the timeline and need to make adjustments within several frames.  I am able to zoom in fully to make adjustments, but it is extremely tedious to zoom & out, adjust the cursor, play the clip, zoom in fully again, make another adjustment, zoom out to see the cursor, etc.   

It would be extremely helpful if the keyboard shortcuts for this worked.  I found the list below on the Adobe help site and in several other online forums, but these shortcuts don't do anything on my system.  I do have the clip selected and have tried different zoom levels when activating the keyboard shortcut, but nothing seems to work.   

Nudge Clip Selection Left Five Frames: Opt+Shift+,
Nudge Clip Selection Left One Frame: Opt+,
Nudge Clip Selection Right Five Frames: Opt+Shift+.
Nudge Clip Selection Right One Frame: Opt+.

Has anyone else figured this out on Mac?  Thanks!