Hello,
sorry for the late response - I had some busy days.
It was the second newest scan essentiels version as far as I know (I installed it in february 2023).
For opening I just used this way:
So I already had a PointCloud open from the former file - SU takes that to the new one - asks if I want to unload it - I press yes and then load a new PointCloud.
For the extensions: I have solidinspector², Benziers Spline (frodo) and the SketchUcation plugin.
I had also contact with another support and they couldnt solve that problem either, so they recommended to update to the newest version - so I did that and nooooow the extension-manager doesnt pop up anymore (Every other window pops up normaly) so now I couldnt use ScanEssentials completly anymore - because it had also to be updated.
After some frustrations I could reinstall the ScanEssentials Plugin over the extension-warehouse.
And till now the snapping-issue hasnt recurred, but I seem to have exchanged that bug with a new one: extention-manager not working 
its not just the window pops up and is just blank - it doesnt even pop up.
I tried everything they said in “Sketchup extension manager not opening - #4 by Anssi”
But I guess thats an new thread.
Cheers,
Micha