Adobe keeps prompting to save file, when it has already been saved

I am creating a pdf from Office and saving it into a SharePoint site.  This all works fine and the pdf file opens in Adobe Acrobat or Reader.  I can then add in Document Properties as necessary and then check in the file through the SharePoint /Office365 option under File Menu.  All Good.  I then go to close the file, either through exiting Adobe or using File, Close, and I get a message saying do I want to save the pdf file?  Very annoying.  If I click Yes, I go round in a loop because the file is already saved, if I click No, then it closes the file.  How can I get to close the file, which is now already in SharePoint and checked in, without being prompt to close it again.