I’ve tested this multiple times with several different maps, the only significant difference I can see is the amount of content within the level. Level streaming, in general, happens very quickly, so a level with little content is not going to show the same hitching as a level with many assets. The hitching occurs, but it may be so small as to be insignificant.
Try moving the distance at which you are streaming the level to prevent falling through the content, does this make a difference? The reason it doesn’t work with “Always Loaded” levels is because these levels have already been loaded, so there is no reason to block again. You can also simulate the hitching using “input UI Only” or other nodes to prevent all assets from moving, but this will require much more backend work to function properly and should be taken into account while building each asset that has movement.