mkv is just spitting DVD's out

[No Idea]

For some time I have been unable to get mkv to rip any DVD. I am using a Mac desktop (2011 vintage) running 10.13.6 High Sierra, with internal optical drive. It still reads CD's (and rips to iTunes no problem), however no matter which DVD I put in, it just whirs and whirs and then spits the DVd back out. No error message, nothing.

As a control, I attempted to rip a DVD I have already previously copied. That was also rejected.

What is the issue?

[Woodstock]

Your drive cannot recognize the disk as formatted, so it ejects it. This is outside the control of MakeMKV.

Most of the time, cleaning the disks will "fix" the problem.

[No Idea]

I did wonder - thank you, I have (obviously) little idea of these things...

Much appreciated.