So, I get an error when trying to save a map, but in my contents I see the map that was not saved, and it opens as expected, so Save/Save As are both having issues. If I publish a service, and I have a layer unchecked it does not appear in ArcGIS.com. If I publish Anno, it appears in Contents, but when I open up ArcGIS.com, nothing appears.
Pretty easy adding anno in Explorer Online, Extremely hard to add Anno via ArcGIS.com viewer, if not impossible.
Oh, and I can Save with Explorer Online just fine.