If you hit Tab and then Escape really quickly, your PDA can get into a state where you see the PDA, but are not in PDA mode (and the PDA won’t respond). If you then hit Tab or Esc to get rid of the PDA, then you can’t see the PDA, but will be in PDA mode (and can’t switch rooms). You will toggle between the two modes with Tab or Esc.
To recover, just hit Tab and then Esc really quickly again. Things then go back to normal. Devs are aware of this and will address it now they know how to trigger it.