I kinda backed away from this topic since I can't contribute anymore as I don't have an XG100p in front of me to test with. What I can say is that if this is something where it worked in RPM10 and stopped working in RPM14, it likely wasn't because they meant to remove functionality (IIRC the XG100p was not getting updates past XGP R02 anyways) it was probably broken while adding something else and since its such a niche option, nobody noticed.
That said, your options are basically roll back to RPM10 (if it worked there) or decompile RPM to figure out where they broke it. I've done this for a few other things where a checkbox would be greyed out when it wasn't supposed to be because of a bug and worked fine, but it can also corrupt personalities and radios.
SC5 files are not supported on the XG100p that I have ever seen, and they can only come from TAC for an extremely good reason. You basically need a multi-million dollar contract on the line and the only way to save the contract is to develop an SC5 to edit something that can't wait for a firmware fix. SC5s are literally instructions sent to the radio to modify an EEPROM location after the personality is written, which lets you mess with just about anything if you know its absolute location in EEPROM.
If I get a radio across my bench I can test with, I'd be happy to debug this but it's not something I'll dump a ton of cash on for a test radio.
Ahh all good! We missed ya.. damn bummer… I’ve read in multiple places including official software documents stating it’s extremely advised against in downgrading firmware versions