This is a guess, but perhaps when there are leaks, the CPAP can't detect apnea events (lack of resistance to air flow?) and vice versa.

I have the same issues.

It also seems like it's a constant battle vs. leaks and I have to adjust my mask. It seems to ride up the bridge of my nose and leaks. The non-adjustable part of the headgear pulls it up.

Net: I need a better fitting mask.