Without knowing your previously fill level it is impossible to tell anything by the photo
If there is trapped air you can try to tilt the PC into different directions while the pump is running at full speed. When you move the system around, keep an eye on the water line within the reservoir to avoid sucking in further air into the loop.
Based on your photo the fill level is also way too high and will cause several problems with false alarms and wrong measurements like the fill level. I would suggest to keep the water level at about the half and test again. Maybe that also already helps somewhat with your current problem.