Question AIO Pump noise

[MDE]

I have one of these CoolerMaster AIO coolers and have had awful pump noise for a while. The noise is present when the fans are off\stopped and I can definitely hear air\liquid moving around the loop when I rotate the case. I have the radiator mounted at the top of my case. I've tried t rotate the case, and interestingly enough, the noise seems to go away when the case is upside down (radiator down) which really doesn't make sense to me. I've tried to get air out of the loop by opening the fill screw on the radiator with zero luck.

Any ideas?