Sorry, always have something to say after the “Edit” button disappears..
What if CG Dra disk is becoming elongated, responsible for the PEHs during or near some of the high-mass transfer outbursts, but then, as its radius changes, becomes circular again, so it does not precess at all? This would explain why PEHs do not appear in quiescence and that there is no beating period. What I am thinking of is a borderline U Gem/SU UMa case with weak temporary resonance events, whereby superhumps are invisible in quiescence and appear only occasionally during the outbursts. Of all outburst peaks, profiles without PEHs were seen 5 times so far, and 2 with PEHs, so roughly half to a third of the time we see those humps at outburst peaks.
But I really like the “partial AD outburst” idea.