when I try to apply a filter from G'MIC , it appears to be working, but the image always remains unchanged. I am so frustrated. I am using Mavericks and McGIMP and have never had a problem before.

EDITING::sorry I just realized I posted this topic here already disregard this

Do you click apply, I am sure you do, but I had to ask.

yes, still no luck. I wish it was that easy of a fix, but a part of me still thinks its something simple like that

Did you try to change the output mode? E.g. use a new layer or new picture as output? Can you please show your G'Mic settings (on the left, below the preview)?