i bought a spindle of 4x prodisc s03 discs from shop4tech and ended up with the mcc 01rg20 discs. surprisingly, they burn at 8x fine on my pioneer 108. here is a scan i did using dvd info pro which has preliminary support for the pioneer. 4x burn:
That’s because Prodisc are now manufacturing discs for Verbatim. Try the Verbatim DataLife Plus discs… they are even better 
If you ordered prodisc and got discs with an mcc media code, you got a bargain. Enjoy. 
Unless you’ve got a 4x drive that likes actual 4x Prodiscs.
Can u provide a link of the exact ones u ordered?