Losing time in a frame rate conversion - how to avoid?

I just ran a Chronos Fast v3 setting with the Slow Motion set to 100% with the output as 24fps instead of the original 25fps.
However, on completion the 24fps version is shorter than the 25fps original by 18 seconds, which is huge.
Original run time was 2:00:59:12 whereas the 24fps Cronos version is only 2:00:41:05.
This is utterly unacceptable because the audio loses sync because the film is running too quickly. How can I prevent this either
A (preferentially) in the conversion process, or
B correct the transformed footage back to the correct run time.

Any ideas would be wonderful

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I’ve always had to use another tool to fix it. Sadly, that usually means converting the whole thing to images then back to video. I’ve heard of people using something like MKVToolNix to change the framerate tag, but that might not work on your video or player.

Oh dear.
That is not good news.
Is there not a slomo setting that can compensate?
Why is it not the right duration - surely that is a basic requirement?

There are prior threads discussing this bug. When increasing FPS, Chronos only works ok at 2x or 4x. For clips under 5 minutes and/or having few scene changes, it sometimes works ok. One poster claimed to have a workaround with Avisynth’s Srestore. I tried that but it didn’t help. I ended up just using a 2x increase, which is not perfect as every scene change has a non-visible frame blend.

Thank you - that explains the 8 or 16 second too fast issue.

How do I find other threads, please? Where are they? I must be stoopid, or hard of seeing as all I can find are mega-threads with both Mac & PC and everything all piled on together.
(I am obviously not seeing something in the forum interface, or else I am just a hopeless old Luddite stuck in the 20th century!)

At the top middle right of the forum pages is a dark graphic of a magnifying glass. Click it and that opens the search dialog. Type in Chronos. However, I may have found the threads with a google or duckduckgo search.

cut / crop the image so that any black bars are gone. processing black bars or borders is a waste of time!