Hello Jim,
1. You are correct, this is the OneDrive for Business library. The file is located in a user's OneDrive library (He either uploads the files manually to the Office 365 Portal -- or he may be using the OneDrive Desktop application to sync it. I need to verify
with him, I just think he now opens up Excel and it remembers the path to the OneDrive for Business libary).
So yes, this is an Office 365 user account and a OneDrive for Business library.
2. This issue happens only when you open the file in Excel. So, you can go to the Office 365 Portal, then to OneDrive and locate the file. If you click the three ...s, you can select "Open in Excel" and it will launch Excel 2016 on the computer.
This is where the problem occurs. When clicking the Share button, you can pull up any other Office 365 user in the company from the address book (It's the correct account, since Skype/Lync also show that that user is currently using Skype for Business/Lync).
Regardless of whether you select the user from the address book, or type in the e-mail address (even clicking the user when it auto populates the names when you start typing), it immediately comes up with the sharing error when you try to send it.
I even tried to change the document from "Edit" to "View Only" to see if I could bump it out of this odd issue, but it remained the same.
a). I'll have to have him try a different program, other than Excel. I don't know if he has tried Powerpoint, Word.
b). Yes, this employee is using his account all the time. However, I did notice at one time he was also signed in with a @gmail.com account. When the problem first started I had him sign out of both his work account, and then his gmail.com account in Excel.
He then signed back in only with his Office 365 work account.
It kind of makes me wonder if I need to delete his other account credentials from the Credential Manager in Windows. Or at least try signing in with a different account.
To me, I thought the same... I felt like it couldn't share, because it was trying to share with his personal account. But, signing out of them both, and signing back in only with the Office 365 account should have worked.