If I switch to another app while editing an article in the mobile app and then switch back, the app becomes unresponsive, the syntax highlighting disappears, typing any text into the edit window has no effect (the keyboard's suggestion feature seems to detect the typing but the characters don't appear in the edit window), attempting to save or go back has no effect, so I have to kill the app.
Device: Nexus 5X
OS: Android 6.0.1
Mobile app version: Wikipedia Beta 2.4.156-beta-2016-09-19
This has been an issue for a while, in many previous versions as well. I don't remember whether it was ever working for me.
Sorry if this was reported before, I tried searching but couldn't find a related task.