I have a similar problem with my Canon HV20. You mention seeing a problem when you play back the tape in the camera. If that’s repeatable then that’s probably where the capture problem is originating. My HV20 drops frames while recording (amazing Canon got away with this). During capture those locations cause skips/breaks in the capture. The pre-roll and post-roll settings also extend the missing gap.
If your camera continues to record with dropped frames then I would recommend cleaning the heads and trying again. Otherwise, not sure what else you can do if the recording is the problem.