Hello Richard,
Many thanks for getting back to me again.
Much of what your are asking from a technical sense goes over my head. What I can confirm is that I am using Pinnacle Studio Ultimate 24, the full package - as I have done for all my other recent film projects without problems.
The source video files used on my current (problematic) film are, as before, a combination of MTS and mpeg files. The first clip is an MTS file. Again, have used the same file type without any export or rendering issues before.
My PC, with a 64-bit operating system, and set-up is the same as used previously to produce films from the same Pinnacle software - ie, Windows 10 Home, Version 21H1, installed last year.
While awaiting a resolution to this current problem, I have just started putting together a new (part 2 of a 3-part series) film - and no red bar shows on the top rendering line. It is rendering in the background as per normal.
Which suggests that there must be a problem with the actual timeline of part one. But why does the red bar show only at the very beginning and nowhere else on the same timeline?
Cheers,
Tony