I'm having the same problem with SR4. It appears that the Source Documents page in QMC is not scaling properly. I see the task description next to the document, but no red X, no pencil, and no run button. However, if I zoom out (ctrl -) until the page is almost too small to read, I can see those icons! I was able to delete by clicking on the tiny zoomed-out icon.
I thought this was just my browser, but perhaps a bug?