This is pretty strange. It sounds like a bad viewport buffer address, but in that case zebra should also be broken.
With the display showing the "linehold problem", press the "Quick dump" button in the debug section of the live view screen, and upload the file here.
How are you displaying from your raspberry pi, is it a physical screen connected to the pi, or are you using VNC or remote X?
If you enabled "UI Overlay", does the canon UI display correctly in record mode and update if you open and close the menu?