Fiery’s support for spot colours via SpotOn, and SpotOn works with a name-matching system. So, if you have a spot colour and can’t make Fiery to accept a spot colour correctly, try changing the name of the spot colour separation in the file to make it match the name of the SpotOn swatch. If you do, Fiery will use the SpotOn colour values.
If names don’t match or the supposed spot colour isn’t set as a separation in the file, the Fiery RIP will cause problems. Sometimes you may run into problems too when transparency flattening is converting a spot colour into a process colour, or when spot colour matching in the Fiery RIP isn’t turned on.
However, there’s a catch. If you are using the Adobe PDF Print Engine (APPE), you can’t edit spot colours. With APPE turned off, you will see your spot colour edits. With APPE turned on, your edits will have no effect.