If there is an Office file embedded on a page and two users start editing it in Office at the same time. The first one to save his/her changes will have the changes uploaded to Confluence. The other one that saves after the first is not able to save at all. Office seems to be puzzled when the file has changed form. Office does not show the changes and does not allow saving. It does not even say that the save has not been made. It just does not save.

This is bad if a lot of changes have been made and it does not inform of the problem. Someone might just save and close the window and realize later that nothing was actually saved and nothing can be found in the version history.