I meant a screen shot in general
Maybe something else is going wrong
What about if you try /nui movers and see if somehow it has moved behind another frame somewhere.
Hmm, also, try /framestack ( repeat to turn off as with /nui movers ) which will pop up a screenshowing what windows are under the mouse. See if anything like Shapeshift appears in an unusual place. I'll confirm the name in a few when I log in my druid.