Dude you are not the only one. Although I
 suppose having a couple drinks while playing "Go find the thing" may have a tiny bit of an effect on that.

Wow... The marker is exactly where the gofannon forge sits. Thought I was going crazy.

Did you go to the forge area? Or did you go through the pools of luminence?

I'm directly on the market and it's not there though

Go to the cistern. Go straight and right. Follow that cave.

It says
 "Arcadian Valley
Head to the source of the signal and open a gateway to the vex network"
It looks like it's in the forge, and I can't find it.

Where is the gateway location for the story mission?