Trying to save a file with two artboards. I tried various types of save, "save as", psd, psb, saving in different folders. One thing that triggered it was trying to save again while it's saving. The dialogue opens saying it can't save because another save operation is already in process. Clicking ok triggered the save to take place. Before that I saw the little progress bar in the lower left, but it was stuck at 0%. The other way I got it to save was by clicking on the progress bar itself. This is after a long wait where it did not make any progress beyond 0%.