PS1 beetle core not detecting scph5501 even though it's there

[QueenNothing]

Been very frustrated with this but I've been trying to play Symphony of the Night and I keep getting an error screen saying scph5501 is missing even though the file is in the ♥♥♥♥♥♥♥ system folder. I've looked around and a lot of people seem to fix it by renaming the file to make it lowercase, which I've done, yet it still gives me an error. Really don't know what the issue is and I'm at my limit with how much of a headache I've gotten from this.

[Dgo]

Is it possible that your bios file has double extension? like example.bin.bin where it should only have 1 like example.bin ??

[Fried Brains]

first load the core and click on 'information> core information' and see if it shows firmware present

[Fried Brains]

also open retroarch.cfg with Notepad and check for: system_directory = ":\system"