sfaust wrote:
it would trip the GFCI every time. We tried having it plugged in and
then turning the switch on as well, still tripped. There is one red
wire coming into the outlet (hot from the switch) and two neutrals
coming out.

NO! There are not two neutrals. There is one neutral and one ground.
GFCIs work by detecting when the current going through the hot lead
does not match the current coming back through the neutral lead.

It sounds like you have the neutral and ground reversed on the outlet
controlled by the switch. It's also possible the light you are plugging
in has some malfunctions. Is is a dimmer light?

Bill Ranck
Blacksburg, Va.