I seem to be having a problem with certain cheats for this game, namely the cheats that require Corwin of Amber such as There can only be one. All the non Corwin of Amber cheats work fine but for whatever reason the ones that do require it don't work. Corwin of Amber itself works but the required ones don't.

Is there a possible bug where they aren't activating?

most of cheat should work after corwin of amber, if you are strying map vision "sally" try "sally shears"

Actually Sally Shears works even without Corwin of Amber. Trust me when I say I used to play this a LOT as a kid (I still have the original disk) and knew the cheats almost by heart. But for whatever reason the cheats that require Corwin of Amber don't work for the GOG version. Theres no indication of if the cheat is activated or not (the cheat that needs Corwin of Amber as Corwin of Amber activates just fine).

I just tried the invincibility cheat (There can only be one) and it doesn't work. Again non-Corwin of Amber cheats (Sally Shears, Hurry up guys, Pot of gold, Iron Forge and Eye of Newt) work just fine its the other cheats that require it that don't want to work for some reason.