Illegal Pokemon Red Dragonite

[AwkwardAardvark]

Hi, I'm playing Pokemon Red and collecting Pokemon. I recently evolved a Dragonair into Dragonite and the Dragonite is flagged as illegal inside PKHeX. It was not flagged as illegal while it was a Dragonair. I have another Dratini and Dragonair that were caught in the Safari Zone just the same as the Dragonite. I have never even made changes to the file with PKHeX; I use it to inspect experience values and other stuff, but it's basically open in read-only mode. I use BGB emulator to play the game.

Not sure how to attach files but I can provide the save file too if needed. Thank you for the wonderful work on PKHeX, it is an amazing tool.