I've noticed the same thing when editing posts (but only sometimes?), where you click save and it "does something" but stays in edit mode. At the very least it does actually save your edit, and if you refresh the page all will be well.
I noticed yesterday that, when I clicked "edit" and went to the "full editor", it had removed all the line breaks from paragraphs, which was weird, but I saved it anyway just to see what would happen and all the paragraphs were still there. This isn't an issue that needs fixing or anything it's just a strange thing I noticed that kinda scared me for a sec.