Whenever I try to convert to AVI I get the green bar indicator on conversion it looks like its all going fine then the conversion program bombs out half way through, I have reduced the file size down to below the 1Gb threashold and its still the same, I have tons of RAM and CPU available...I am baffled normally this process works effortlessly, I am using 4.8.6.3 x64

Are you still having this issue? If not, how did you resolve it?

Still having same issues, when I convert to AVI, on playback half the footage is missing, I've tried reducing the clip but still does the same, I have gone back to using the supplied REOLINK CCTV software, massive files but at least it works.

Being your still on BI v4, I can't help since the differences between v4 & v5 are great.
I think I may have had issues with .avi when I was on v4. I'm using .mp4. Have you tried exporting as .mp4?

I would suggest contacting BI support, if you haven't already.