Sudden rise in AHI with Philips mask

Hi all !
Great forum as a newbie.
Could you give me some advice ?
I had a sleep study, 28 events per hour, 90 obstructive.
Started CPAP 6 weeks ago with Resmed 10 Airsense Auto.
Auto ramping start at six, max pressure only 9.6 was enough EPAP 2. Setting displayed CPAP with my first machine, now APAP again...
Started with a ResMed n30i mask, noisy, waking me up 15 times a night but my AHI dropped to 1-2.
Lost out on sleep because of frequent awakening and needed chinstrap, so switched to Resmed Full face mask F20. problem: itchy nose drove me crazy ! But still AHI only between 1 and 2 so great success.
# days ago bought yet another mask: Philips Respironics newest model with mouth mask and on top of that sits a typical nasal pillow. GREAT ! Sleep 7 hours without waking up. BUT: had it now for 3 nights and eat h night had my AHI between 16 and 18 !!!!! Horrendous.
So, the only mask that is comfortable makes my CPAP useless as the AHI becomes unacceptable.
I am now increasing my pressure to 12 and step up further, but what else can this be ?
Would love to keep that mask.
Thanks !

Welcome to the forum.

What category of events is the increase in AHI primarily?
3 categories
ClearAirway/Centrals
Obstructive Apneas
Hyponeas

What is the breakdown into each category of that AHI of 16?

Kind of important to know because not all the categories respond to "more pressure to kill apneas" thing.