Question
Why does my share button not work?
Answer
The share button utilizes SharePoint Share to send email notifications. If your share button does not send email notifications or displays an error message when you attempt to share content, your SharePoint tenant settings may be configured so that items cannot be shared.
You can find information on changing this setting in Microsoft's documentation here: https://docs.microsoft.com/en-us/sharepoint/turn-external-sharing-on-or-off