I'm sure I saw an X2 video clip where Pro channel FX chain presets could be dragged straight from the browser to the Pro Channel.

When I attempt this all I get is the black circle displayed over my curser as if to say "you cant put that here buddy"
I can load FX chain presets fine once I have a chain module already in the Pro Channel but obviously this is a more convoluted way to do it.

Did I imagine this drag and drop function for PC FX Chain presets? 

Pretty sure it works here.
 
I've dragged a few FX chains into proChannel without any problems.

No - I just dragged 2 fx chains into prochannel. The mouse cursor has a + sign hovering over the top of the pointer.

I had this same struggle. The trick is the Browser tab you need to use. One browser tab is for FX and one is for like loops and things. If you find your FX using the loops and things tab, you can't drag them into the FX Bin. If you find them on the FX tab, they drag over quite nicely.

I'm not sure why they don't make it work either way, but it's probably a matter of bandwidth. Since you and I have both had this problem, I'm sure there are others. Maybe one day, they will advise you with a message to do it from the other tab or just make it work either way.

Well spotted gswitz.....I was starting to pull my hair out!

Seems odd to have two separate browsers but there you have it, hopefully they fix this at some point.

Thanks!