I can't copy grades on a 2011 i7 iMac AMD Radeon HD 6970M 2048 MB.
Middle mouse button, no. When I copy and paste a still, no. When I try in timeline nothing. Oddly enough, when trying to copy still from gallery, half the screen in the viewer goes black. Also on my external monitor, half the screen goes black. Any suggestions please, many thanks in advance.
Also my 2013 iMac has no problems with the same project. Maybe the video card, I don't know.