1. Open chatbox keyboard.
  2. Start typing. Notice how sometimes certain keys are inactive/unclickable depending on where the keyboard is placed.
  3. At some point when typing, there is a chance that you randomly respawn or recalibrate, as if you had clicked the "respawn" or "calibrate" buttons on the handheld menu. This may need a few openings and re-openings of the menu and keyboard to occur fully, as it is very inconsistent for people who use the in-game keyboard a lot.
The thing that makes me think it is the quick menu being invisibly clipped into the keyboard is because of certain observations when moving the keyboard around. If you pull the keyboard directly above or below you and start typing the issue seems to disappear. I assume this is because this places the keyboard completely out of the way of any overlayed invisible menu so there is no risk of it clipping into the keyboard. Interestingly, this problem does not seem to go away when moving the keyboard to the side, at the same elevation.