Hi all,
late to the party but looks like it similar issues still occur in the current day and age. I was using 4.25 and after Open Level node, physics was completely disabled. Solution posted by SarperSoher did not work for me at all, entire physics was disabled (despite my enabling simulation post level load).
Turned out the issue was that the path I was using to load the level was causing problems (not sure why). Despite it loading the level correctly, it was messing up the physics system.
I was loading: /Game/Maps/FolderName/MapName.MapName as this was the string I obtained from Soft Object Path structure. When I changed it to load the MapName only instead it worked just fine and now physics works just fine with Get Base Filename node.
More visually:
Hope that helps someone.
Cheers,
Dawid