Host Migration issues are not due to target quitting.

Me and my friend were playing and the host quit, it started to migrate and I got "unable to migrate" and he got host. This happened twice today.

Host migration issues have a lot of factors. The target quitting is usually the cause of a closed lobby on migration. If just one person drops the game, then that obviously isn't the cause. Could have been a momentary connection problem or some random glitch.