Well my Sunday smoke was ruined by this issue, and I'm done using the MES bluetooth app for good since it happened with me just two days ago. The only way to fix this when it occurs is to turn off the MES and turn it back on and manually reset temp/time via control panel and NOT use the app. I thought my smoker was a goner and going to have to be returned to the store when this happened, but stupid me didn't realize it was my phone doing this with the app running from the other room.
I started searching online and wasn't able to find much info until I went to the Google Play store and came across dozens of folks reporting this issue in the Masterbuilt reviews when using the newest iterations of Android hardware. (I have a Galaxy 7 something or another).
No the MES is not going to make it to 800 degrees, but it will hit a good 375 since it locks the heating element to the always ON state. I ruined a good 4 slabs of ribs, unless you like bone in jerky. Yes a nap was involved.. I'm not as mad as I was 2 days ago, but damn.. thought I should put this out there.
Screen shots below are from recent reviews on the Google Play app store.