Synchronize teaser config file Issue
I cannot say what exactly is the problem (it is a bug for sure), but here's how you solve it: Go to the "Manage Display" tab for the content types for which the teaser display setting is not imported.
On your DEV instance go to the teaser display and save it without changing anything (or changing something if you want to).
Now export the config and push it via Git.
Re-import on Stage and it should import cleanly now.