tapping on an mxid produces broken layout on iphone x, and you then can't start a DM

tap on an mxid; see an ugly screen with a blank title bar covering half the avatar; tap the 'start dm' button; see nothing happens

Start by reproducing the issue on an iPhone X: tap an mxid, inspect the broken layout, then try the “start dm” button. Trace the mxid flow and button action; done means the title bar no longer covers the avatar and tapping “start dm” opens a DM.

Written by the indexing model from the issue text.