I'm not sure what is your problem? I mean, what path in IGR Path you've set for OPL, e.g. "mc0:/APPS/OPL_1357.ELF"? IGR will not work when mode 6 is enabled. I can test RRV (PAL) through USB with OPL 1357 if you like, but from I remember at least "normal" IGR should work (kicking to OSDSYS). Instead of using "latest daily OPL", check in "About" page, what is your OPL rev. Here is also (under table) quick guide how to do it: https://www.psx-place.com/resources/automated-daily-build-system-for-opl-wle-fceumm-ps2.702/.