I actually found a fix!!! Use your browser's HTML inspector, find the sprite editor window and delete the element. Then look for another element called 'dimmer', which is responsible for dimming the rest of the IDE while you edit your sprites. After deleting that element, I had access to the save button! I hit save, it successfully overwrote my cloud save, and when I opened a new tab and went to load my cloud save, it was the most up-to-date version that I had saved only moments before!