Just reading this post and seeing that there’s no problems when one controller is plugged into the headset. This could mean that there’s a wireless data parsing issue, there’s two steamVR tracking dongles in Index and Vive headsets and I’d assume that Pimax also has two internally inside the headset. I don’t know though if Pimax headsets have two internal dongles or just one
There might be other people in your house using wireless.
Have you tried to isolate yourself from all wireless signals and turn all the wifi generating devices off to rule out wireless interference being the cause of the tracking issues?