I upgraded to 2.2.7 from 2.2.6 and at first everything seemed fine.
Then some days later one of my users made some changes to the media tags (deleted a tag and moved some images over to another tag). After they were done, they came running because the media tag pages looked busted.
It seemed as though my mediatags.php template was no longer being used.
That's the thing that makes /media-tags/exampletag/ , and lets me make a customized/archive view. It seemed to be falling back onto my default template.
Once I downgraded to 2.2.6 everything went back to normal.
I tried a few things like clearing caches, re-saving permalink settings, and even de/re-activating the plugin, but nothing worked.