I updated my Nexus 5 to Marshmallow a few weeks ago, however since then I've been having issues downloading MMS messages. I had turned off the "Auto-Download" feature a few months back when we got the Stagefright email, and don't really want to switch it back on to test if this is the problem if there are still vulnerabilities.
I checked the Google Forum, everyone that was having the same issue was either because of Pushbullet (Which I have never had) or an issue with service provider Cricket. If anyone can help me, it would be much appreciated because most of my friends have iPhones so we can't use Hangouts together. Thanks!