Why after saving my excel 2013 file to sharepoint (skydrive pro folder sync) can I not also save as pdf without closing file and reopening?

I have tried both the export and standard save as pdf methods after saving as an excel file and it closes the box without saving the pdf at all. Close the file and re-enter and it saves fine as pdf using either method. There must be an answer to this............................but I just cant work it out!