Been working on a level for a while; suddenly, it broke!
When I press play, I am unable to control my character. The camera moves to some random point in the ground. As a result, I am now unable to do or test anything. Here’s a view of what the camera does. Anyone have any idea what the hell is going on?
Have you tried changing the the default character and seeing if it behaves any differently?
Yes I have. No dice. 
Are you using a “Player Start” actor as the spawn point for your character? If so, what is it’s “Spawn Collision Handling Method” set to?
I tried with and without a palyer start and went through all the spawn collision options. Nothing works.
Every time that happened to me the issue was with the Player Start actor being too low (either touching the ground or partially underground).
To see if that is the issue, move the player start actor far enough above the surface so that your character will fall to the ground when you hit play. If he falls and everything works properly, all you need to do is adjust the player start so it’s just above the surface.
Hope that helps!
TO ANYONE ELSE THAT HAS THIS ISSUE:
I just found out what the issue was! Apparently my landscape was TOO LOW in the Y-Axis and despawning the player character. I’m not sure why it was despawning, but it was. I moved it up like 5k units and now it’s fine. UE4 is so weird.
See here: UE4 Landscape/Character interaction issue - YouTube
My hero <3 i’ve been trying to deal with this all day. I’m even bookmarking this answer!