I've been having a frequent problem with inDesign recently when trying to edit files.
For example, if I try to move a photo from one place on the page to another. I click on the photo and drag it to where I want to go. My cursor moves, but instead of the image moving, I get a beachball for several seconds. Eventually, the image does move, but then maybe 10 seconds later, it reverts back to its original position without me touching or doing anything. Restarting inDesign seems to temporarily resolve this issue, but it comes back again a few minutes later. I've attached a video screen recording of this happening.
Things I've tried:
-Resetting inDesign preferences
-Toggling GPU rendering (happens when it's both on or off)
Using a 2013 Mac Pro (Trashcan Style) running Big Sur 11.4.
I would check to see if some other system process is hogging your CPU. Open Activity Monitor and keep it open during an InDesign session, and when things "stick'" and beachball, see if there's something in Activity Monitor that's taking up a larger percentage and take note of it; It could also be causing ID or any other app you have open to appear in red as "Not Responding". If it's an Adobe-related Process (almost anything with CC in it) then we can narrow it down or eliminate it as the cause.