I have a very simple pawn blueprint setup, containing just two cilinders, one of which is parented to the other:
In the editor viewport it looks correctly, they are both showing up:
However in the level editor and in the game preview only the child cylinder is visible, despite both of them being set as visible and not having any code that could change that.
The problem appeared after adding the second cylinder and making some changes to the constructor, however hiding or deleting the child cylinder or unplugging the constructor does not show the issue.
I’m guessing this is either a bug or some sort of functionality in the pawn parent class that i don’t know about since i didn’t make any changes related to visibility.
Edit: It also refuses to simulate physics as soon as i press play. “Is simulating physics” returns false despite it being set to true in the blueprint. Setting it again at runtime also does nothing. Currently i’m using a workaround where i hide the mesh and replace it with a copy of itself that is parented to it.
u check the “hidden in game”? 
“Hidden in game” isn’t on. Also keep in mind that if it was just hidden in game it’d still show up in the scene viewport
Could it be that both have a collision and one of the 2 flies away and cannot be seen?
The cylinder that stays visible is attached to the one that becomes invisible, so if it was to fly away both wouldn’t be showing up. Also, if it was that it would be gone when i start the game and not in the level editor since. Duplicating the blueprint just solved it oddly enough (i didn’t make any changes to the duplicate before it started working).