In another post, I resolved a problem by adding 'convertToRGB24()' to an .avs script.
That solved the problem for Subtitle Workshop.

When I used the same avs file in DVD Flick it showed the imported video thumbnail upside down (and converted to DVD same).
When I removed the line, it was ok.

Just wondered if this was typical.

https://forum.videohelp.com/topic367011.html?sid=d01b741116e0226970d05711da02b763#1959438