We also encountered this problem in our lab. Exactly as described, the fpga blocks/icons became "hidden". I discovered that basically a large section of my vi window had some type of Bermuda triangle (for lack of better description) where any fpga block/icon "disappeared". Well, I found an EASY solution. Select your entire vi, and move it. I selected my entire vi (highlighted everything in the vi) and dragged it to the right, and eventually as I kept dragging it, the fpga icons/blocks appeared again. I could even see the boundary of the "hidden area" where if I dragged an icon/block over the boundary, it would disappear on one side, but appear on the other.
