This is a known issue with the Wyze Cam Pan V1 and CamPlus.
The issue was reported back in June and Wyze has acknowledged the issue. I have been working directly with the Devs via PM to pinpoint the problem.
I have also been testing the Beta Firmware in an attempt to rectify the problem, but it still persists.
It is related to the use of the Motion Tracking (the auto pan and track feature). You may find that turning that off will result in full length motion videos. For some reason, the frame motion in the pan is translating into a stop in pixel motion for the cam and therefore stopping the motion recording.