I manage to check some Memory Calculation reports by creating a new map and coping all art assets (no devices) to that new map, start a new session with that map as default and then run a memory calculation. If you are using world partition streaming, remember to set it up as the same as your original map (copy paste that information didn’t work for me, so I took a screenshot and then replicate it).
It should run the Memory calculation and finish without freezing, then you can optimize the Art part of your map.
That would let you do some optimization but your original map will still freeze.
I’m still looking what it might be the cause of the freezing while we wait for Epic’s patch.
I notice that some settings in world partition (like the name of the first HLOD layer is no longer “none”)
Also HLOD layers have changed, no longer can select instances or merged or any other type, is just one (which is hidden). So I’m right now testing re work my map HLOD settings with a new HLOD Layer to see if that is causing the issue.