There is an option to show or hide PS1 games in OPL configuration, have you enable it ?
Otherwise your file structure should be like this:
hdd0:/__.POPS/SCUS_000.01.Game1.VCD
hdd0:/__common/POPS/IOPRP252.IMG
hdd0:/__common/POPS/POPS.ELF
Everything is uppercase sensitive, so make sure your...