I don't really belong here but I may have an insight for yall...
When I rewrote the boot code for my GIDE to use on the 4p, I had to tweak the status results... tho I don't remember right now exactly what I had to change, IIRC there was a bit set that equates to an error in the old MFM result...
... and now that I think about it, I believe it WAS the '8' in $80... which I think I masked out.
Something to look into. :D