Should I just grin and bear it?

I have gone from having lots of responsibility at my law firm to sitting at a desk twiddling my thumbs on client secondment- Should I just grin and bare it or talk to my training supervisor and see if I can change?

I am on my third seat on client secondment, but I am really not enjoying it. I have gone from having heaps of responsibility and tons of work to sitting filling out forms all day. The problem is, it is a big client of my law firm so I don’t know what to do? Should I just grin and bare it or talk to my training supervisor and see if I can change?