Office365 OneDrive Share - Link cant be sent to external email address

My problem was solved after troubleshooting several items with MS support. The cause of the issue in my case was that the external email address that I was trying to share to was listed as my secondary email address for account recovery. Changing my secondary email address solved the issue for me. If that doesn't work for you, the problem may still be that the email you are trying to share to is registered in your instance of onedrive/sharepoint and you may end up having to take steps to remove it manually through powershell (which was what I almost had to do). Unfortunately I do not have the instructions on fixing via powershell, but you could try googling it as I think they are available somewhere. Otherwise call the support team.

Best,

MVR