On the T-Rex supercam, the 4.5 and the updated 4.6, there is a secure chip built in, which is where the non public hacks are kept.
When Premiere stopped using their MECM encryption it was open on emulations so the 0501 ident worked, once Premiere went back to using MECM it only opened on only the Diablo, the T-Rex super cam, and the Anaconda card, since then I believe some receivers have it open, but it still isn't public.
When Premiere added the MECM encryption it wouldn't open on the T-Rex 4.6, I believe due to a conflict with the 0501 ident, once this was removed and the security update carried out Premiere opened again.
Since then Premiere changed their key, so a new Predasaur file was required, with the updated key in the secure update, since this is a secure area we can't carry this key upgrade out ourselves, but have to wait for a new file, which Kink provided a couple of days later.
There has now been another change in encryption, this time for D+, which has resulted in only the Dragon and T-Rex cams being unable to open D+, and so we need another new file with the fix.
I seem to remember this happening before, to the older Dragon Cams, but can't recall the exact details, I just remember having to program my old Titanium card, and D+ opened using that and the Dragon.
Hopefully a new working file will be produced soon.