Watchable DVD but only 6 of 12 files copy?

[Thing1b]

Donating my copy of a doc to a library, so I wanted to MakeMKV a copy beforehand.

No luck. Same 6 of 12 files keep copying (but not one of the three main feature files). Clean, smooth, not blemished surface, restarting both app and computer… Any suggestions? Any thoughts?

[Woodstock]

No information on why the failures occur, so really hard to say why and how to fix.

[Thing1b]

Yes, apologies, pretty sparse, but I was baffled that a watchable movie, a low budget doc no less, would fail a MakeMKV copy. Figured, it must be a thing.

So, I bought more copies, two more (so, three in total), but every one – all brand new DVDs – failed the main feature…

The only notes; “The source file XXXXXX is corrupt or invalid at offset #####, attempting to work around” of which there were five instances, yet four tried twice,* then the next instance popped up…

* Preferences/IO/read retry count is “6.”

Changed (checked) Preferences/General/Log debug messages and Preferences/General/Show AV synchronization messages.

Changed Preferences/IO/Mac OS X *_KEY_V2 ground type, to 2.

Ran it again, and after the same ‘workaround’ notes I now see “DEBUG: Code 1730 at W.)zml@Tw’C!Z)8V3\:29393746”

Below that: “LIBMKV_TRACE: exception: MKV_ASSERT: TimecodeDelay >= int16(0x8000) && TimecodeDelay <= int16(0x7FFF)

Any thoughts?