Move the scope trigger point down so that it only catches the low going sync tip hence will display a stable line image. This will make the scope captures much easier to see.
As a test try swapping the good and bad inputs to the TVP. This can be achieved by lifting the TVP input coupling capacitors and re-soldering them in an upright orientation, then bridge a wire from the now floating top of the capacitor to the alternate TVP input capacitor pad. This will help determine if the root cause is before or after the input coupling capacitor.
BR,
Steve