Trying to export a GIF with Transparent BG but No matte option?

Greetings! Despite trying to look for answers to fix or find a way to finally have the matte option enabled to just save a transparent GIF but so far no luck. Tried changing the stage color to near black (#010101) but it still greyed out. (I use adobe animate CC)

Is there a way to fix this? I am not sure if this is a bug or anything. If not, I appreciate the advice given!

Much kudos!