When I open World Partition Window (so I can load some cells) editor freeze. It’s looks like it stuck in some infinite loop. Debugging show that it stuck in WorldPartitionEditorSpatialHash.h
To be clear, I can load WP level, or even play it, clicking on this make editor freeze
I just found that if you have a Static Mesh Actor in your scene with no Static Mesh selected for it’s attribute it will cause that freezing.
Maybe one of your objects has a null attribute in it that is bugging the World Partition.
Try opening a new map without anything in it to see if it’s caused by the objects in your scene.