I think theres not enough space for airflow, I tried it and my psu fan (heat controlled) stopped pushing air (well there was just little airflow but i got scared ) and dont know is it safe for power supply. but ill flip mine when summer comes and ill do hole in bottom for air intake, i recommend to do hole too
I might do a hole then. Maybe it'll be worth putting on some taller feet to compensate.
BTW, when you say "stopped pushing air" do you mean it got hotter?