I have a similar problem in LO Writer. Both right-mouse cut/paste and CTRL+X/V recently began acting up. It cuts, but then it pastes something old. It works as it should some times, normally if I try again and again.
Never seen it before, and it only happens in LibreOffice, not in say Firefox.
LibreOffice 6.3.3.2 in vanilla Ubuntu 19.10. I have no idea what a compositor or Mutter is.