ddrescue: 0% rescued on audio CD with 1 track that skips

I'm trying to get some lightly scratched albums (audio CDs) onto my computer via ddrescue. I ran the program on one disc with one track that has skipping problems, and it rescued 0%. The .iso was unmountable. I tried safecopy (ran for 3 days) and also ended up with an unmountable iso. I've tried a couple of different command line options, to no avail. Sudo and non-sudo.

ddrescue -f -n /dev/sr0 /path/to/iso.iso
ddrescue -n -b 2048 
ddrescue -f -d -R --force

I've tried ddrescue on another CD without any playback issues and still got 0% recovered. What gives?