I have two phones on my account both Moto G4 Plays. Both units just recently received the android 7.1.1 update and since then whenever anyone sends them a mms containing a mp4 it gets split into a jpg and a qcp file. Prior to the 7.1.1 update this did not occur. They are both using the stock android message app. I have a moto E4 running 7.1.1 and using the same app I can receive mms containing mp4 perfectly fine.