about this post:
I have given a quick look at this problem and it is sufficient to copy the 5.08 version for
mockup/patterns/resourceregistry/js/overrides.js
launch
bin/plone-compile-resources -b resourceregistry
and reload the page for the resource registry control panel to fix this regression from 5.0 to 5.1.
it seems that this commit broke it.
When removing it, resources personalisatons are saved again. Now I am not sure that they can be accessed, I have to check the python code for overrides.