Win95 and up used Joliet for an LFN, extension. The standard requires an ISO to retain an 8.3 mapping using DOS compatible characters to the raw data. Rock Ridge and Joliet in turn map LFN data to the 8.3 file names without interfering in the basic function of the filesystem. This is transparently presented to the user on platforms that support it and ignored in those that don't.
I'm guessing that the base ISO9660 data simply wasn't mastered according to standard which resulted in an incompatible disk. Poking around Wikipedia, I see that there were other "standards" which didn't preserve backwards compatibility that could also explain this issue.
https://en.wikipedia.org/wiki/Romeo_file_system