All entities disappear when in spectator mode

My old singleplayer world lagged out and whenever I tried joining it, it froze on the loading terrain screen. I tried everything to fix it but nothing worked (I was sure the problem was somewhere within the level.dat files but still didn't know how to fix it) so I recreated the world with a copy of the DIM1, DIM-1, entities, and session.lock files. Then whenever I go into the newly created world and go into spectator, every entity disappears. This includes all mobs, item frames, minecarts, and armor stands. I have never had this problem before or with this any of my other worlds. I have an example in the attachments. Can anyone find out the problem? Thanks!