My renders are missing assets and for some reason extending the length for no reason.

Hi
Not sure what is happening, but on my old iMac I have the AE 25 and I rendered out a video this afternoon and it was fine. So I thought I would pre-render some that I did a few years ago. I opened them, checked everything was there, trimmed them, and prepared for render. I added to ME and it said ready. Set it rendering and came back 3 hours later, and all three videos had some elements missing, and then after the main section it seemed to add like 20 minutes of blank video, that isn’t even in the timeline and then the end credit section.

Does anyone know what this bug is?

Thanks

Rob