Handbrake refuse to RIP a disk

I have been using Handbrake for a few years and never had a problem until now. I have a box set of Back to the Future. It refused to RIP the first disk in the series no problem with the others. The disk is in perfect condition and plays through on VLC without a hitch. Has anyone got any ideas?

OS Linux Mint 19
Handbrake version 1.2.1
Dependency,libdvdcss2 version 1.4.2-dmo1 is up to date.

Any ideas?
Thanks.