Migrated level disappears when play testing

I am running 4.11.2 on OS X 10.11.4
I have an level that I created in 4.10 and migrated to 4.11, which works fine in and of itself when play testing in 4.11.2. I’ll call this “Level A”.
I want to merge this level with another level that I created in 4.11.2, “Level B” so I opened “Level A” and right clicked on the level in the content browser and chose Asset Actions>Migrate and migrated “Level A” into the content folder for “Level B”.
I then opened “Level B” and selected Window>Levels>Add Existing and chose “Level A”.
In the editor everything is fine - I see and can edit both levels in the view port, I can see both levels in the content browser.
I build everything out, click play and two main issues occur - First and foremost, the migrated level completely disappears, secondly the avatar doesn’t start at the player start, but rather falls from the sky. There is only one player start, and if I right click in the view port and select to “play from here” then my avatar does play from there, but the migrated level is still missing until I exit playing.
I’m assuming that because these are two separate levels, then there must be a setting that I’m missing to include both when play testing, but I am unable to find documentation. Please help!