Question Private Mode Question

Background: I'm on a stock rooted rom. After I rooted Private Mode still worked. Now it does not for some reason.

So I have a few questions.

1. Any idea of where private mode stores the files? I had a few GB of data stored in there, now that its not working I want to make sure I no longer have those files clogging up precious GBs on device storage.

2. Is the only way to get it back is to re-flash the stock rom?

3. I think I might have broken Private Mode by trying out ART. Now when I go into Developer Options, I notice that it always says Dalvik....When I switch to ART and reboot, and check the Developer options, it still says Dalvik. Any thoughts on this?

Thanks for any thoughts.