Weird issue with guitar lesson DVD

[george14215]

This is not a critical issue, but I thought I'd report it...

My DVD plays on multiple drives. But MakeMKV is unable to either make a backup or make an MKV. It just churns away with the remaining time growing and growing into double digit hours.

On my mac was able to make a DMG image via Disc Utility then convert it to ISO.

When using MakeMKV to open the IFO file on the mounted DMG image or open the ISO, I get this error

Using direct disc access mode
Complex multiplex encountered - 4 cells and 1750 VOBUs have to be scanned. This may take some time, please be patient - it can't be avoided.
Title #1 (1:39:16) was skipped due to navigation error
Failed to open disc

The converted ISO plays fine via DVD Player or via Infuse on Apple TV accessing the ISO remotely via SMB.So I'm pretty sure the disc and the resulting ISO are fine.

[dcoke22]

There are different opening modes for DVDs. What happens if you try a different opening mode?

[george14215]

CellWalk
Using direct disc access mode
Failed to open disc

CellTrim
Using direct disc access mode
Complex multiplex encountered - 4 cells and 1750 VOBUs have to be scanned. This may take some time, please be patient - it can't be avoided.
Title #1 (1:39:16) was skipped due to navigation error
Failed to open disc

CellFull
Using direct disc access mode
Complex multiplex encountered - 4 cells and 1750 VOBUs have to be scanned. This may take some time, please be patient - it can't be avoided.
Title #1 (1:39:16) was skipped due to navigation error
Failed to open disc

Note, while Infuse can open the ISO file and play it, VLC cannot. All my physical players can play it. I can provide you with any file you want if this something the developers want to look at. Again, it's not an urgent issue for me. I just really like this tool and reporting what appears to be a bug.

edit: added clarification to "players"