Acrobat Reader Android Problems with "Save a copy" or "Share"

Hi,

I'm trying to save a PDF file (annotated) which was opened with Acrobat Reader Mobile from a OneDrive folder.
If I select "Save a copy", I can select the OneDrive folder where to save and a message appear "Saving a copy of the file. You will receive a notification when it is finished", but nothing happens and no notification is received!
If I select "Share", I can select the OneDrive folder where to save, but the existing file is not overwriten and a new one with the same name and a "1" is created.
This second option is little annoying but menageble.
 Why the first is not working?

All this is due of the fact that OneDrive Mobile will not allow me to set Acrobate as the default Viewer for PDF files....
Thanks, Lauro