Hi Kirk
I've also - sometimes but not consistently - had the same hang when just selecting a single item in a sub-collection sorted by arrangement and when adding some files from a search window to a collection sorted by filename.
Other inconsistent anomalous behaviour:
2 windows. One has a collection sorted by filename the other a search result for multiple filenames. i select a few in the search and ctrl click-> add to collection. I briefly see the collection count incremented but then the window reverts to the parent collection. I can select the sub-collection OK and all seems OK after this.
I move a file in a sub-collection to a new place in the arrangement and all the images become grey squares. This persists, I try other collections and eventually (2 or 3 minutes) images reappear. This may just be because of the passage of time, not my random clicking of other selections.
I have a contact sheet of images from a search for multiple filenames. I choose to show selected or tagged and this takes 2 or 3 minutes.
I've left the logging turned on but have had to force quit multiple times so I have no idea if the log will be of help but I've attached it here anyway.
David