Hello. It seems that my camera also has this issue.
First of all, I wanted to mention that I am using a 1Tb Sandisk Extreme Portable SSD (which is included in BMD ‘Approved SSD List’). When I record any possible ProRes video (DCI 4K, UltraHD, FullHD, no matter what frame rate, ISO or shutter is) and then I press the ‘Play’ button to playback the video, the camera fixes a static image of what is in front of the lens at the moment of pressing the ‘Play’ button. And, when I press to playback the recorded file, the screen starts blinking showing both the recorded file and the static image of what was in front of the lens. If I put on the lens cap or detach the lens putting the camera cap on and then press to play the video, the screen starts blinking showing both the recorded footage and the black colour. When I connect an external HDMI monitor, the result is the same. Both the camera screen and the monitor screen blink.
However, when I record any type of RAW, everything works fine. The camera does not fix a static image. It immediately shows the recorded clip and plays it with no issues.
Moreover, when I upload the ProRes files (which were blinking in the camera) to the computer, they also look fine. No blinking.
I include the video I recordered for BMD Support Team showing how this issue appears (sorry for my English). The footage created during the test can be found below the video on YT.
By the way, I also tried other media storage and the result was the same. I tried formatting both internally and using my computer. Nothing changes. I tried formatting both exFat and HFS+ but it also didn’t help. So, it is obvious that storage has nothing to do with the issue, and it is in-camera problem.