I have used MakeMKV for about a year or so and have ripped many hundreds of dvd discs and a few blurays. So far, MakeMKV has never failed me, if the discs are 100% clean and have no scratches.
If a dvd disc is not sufficiently clean, a READ or MEDIUM error may ensue, but other debug messages are also possible. I have seen many awkward debug messages, but in my case they always referred to the one and only problem: the disc is not completely clean.
The definitive solution for this problem is cleaning the disc with a hygienic wipe and try again, perhaps in a different dvd reader or after a reboot of the laptop.
Some dvd discs have these peculiar circular stripes. I don’t where they originate, perhaps it is a production issue but it could also be caused by usage in a dvd reader, but MakeMKV does not like them. Use a (alcohol soaked) wipe until the stripes are gone and MakeMKV will succeed.
In my experience, scratches on discs are a lost case. I have tried polishing scratched dvd discs, even used toothpaste but never to any avail. I have also seen rare cases where a dvd disc has clearly visible production issues, like a spot or stain on the disc. Naturally, it is unreasonable to expect MakeMKV to function correctly in those cases.
There is just one case where I had to use manual mode in MakeMKV to rip a dvd and the problem was caused by wrong size information on the disc itself, i.e. a mastering issue. Even VLC got confused playing the dvd. It was a miracle MakeMKv was able to rip the dvd in manual mode at all.
MakeMKV is a terrific product created by expert people who know what they are doing.