www.makemkv.com

Using MakeMKV 1.9.4 on MacOS 10.9.5
DVD is "The Englishman Who Went Up A Hill But Came Down A Mountain", R1
Only a single small track is found - it appears that the main track cannot be parsed.

Log:
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Using direct disc access mode
Complex multiplex encountered - 22 cells and 10594 VOBUs have to be scanned. This may take some time, please be patient - it can't be avoided.
Title #1 (1:35:41) was skipped due to navigation error
Complex multiplex encountered - 1 cells and 232 VOBUs have to be scanned. This may take some time, please be patient - it can't be avoided.
Title #2 was added (1 cell(s), 0:02:05)
Operation successfully completed
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Handbrake sees the first track correctly.

What info would help to debug?

Navigation errors can be tricky. Mike has said that some drives do not report proper error messages when a disk is actually unreadable, and you end up with invalid data and no way to tell what was supposed to be there.

On DVDs, you can tell MakeMKV to manually select the problem track, but there are no guarantees that it will be able to find all of it. See http://www.makemkv.com/manualdvd/ for more information on that option.

You might try cleaning the disk. Yes, it sounds like a cliche, but it really does fix a lot of issues. A fingerprint in the wrong place can cause issues with finding all the pieces of a file.

I had a disk that was unreadable, the surface was pretty much destroyed. I'd kept it in its case for a while but had discovered the disc was on sale at JB, so I took it out for one last try. Not expecting it to work and fully intending to throw it out I rubbed the thing with my thumbs, put it in the drive and it worked perfectly. Apparently the oil or whatever on human fingers does a pretty good job of filling in gaps and making discs readable, I've done it several times since and it's saved some pretty screwed up discs.

(We don't have Pledge here, I bought the closest substitute I could find but it didn't accomplish much.)

Never thought about "just" using your own body oil as a subtitute for wax, but I have dry skin, so it won't work for me.

Many generic furniture polish/wax formulas will work at least as well as Pledge... The key is a water-based wax, which won't chemically attack the surface, and no abrasives. Many car wax products could be used, too.

If the clean/wax method doesn't work, the next step is best done with proper equipment. I've substituted tooth polish and a finger rub at times, but resurfacing a disk is best done with the proper tool.