I am not sure if anyone here has experienced the same issue.
I find it easy to move objects around while activating a section plane, rather than switching off tags etc. to get access to that object. I have since a couple of updates ago realised that Sketchup crashes often when doing this and it is extremly disruptive. You should be able to move objects around while a sections plnae is active.
I have started to think that it is a MacOS issue as two of us in the office have the issue. And we have identical machines. The rest are running windows machines.
I haven’t been able to reproduce this using simple models on my Mac. I wonder if it involves some extension you have that I do not? If you can share an example model, I will try with it.
This is a very frustrating issue as I myself am not able to duplicate this on demand either. I will unfortunately not be able to share any of the models. It seems to be a hopeless case. I am trying to capture this issue and share it here but am failing to do so. I will share when this happens again.
Are you running SketchUp with the new graphics engine or the Classic one? I understand that some older Macs (you say your Mac has a Radeon graphics card) are incompatible with the new engine.
I do know of something we fixed that happened when bringing something into an area of the model that was under a section plane. The next update from us should have that fix in it. I can’t yet say when the next update will be released.