Adobe Sign Outlook Add-In

Issue with Adobe Sign using Outlook add-in. What happens is we can add the recipient and file and then click Send and we just get this grey blank screen, see attached. Sometimes it will say "processing", but usually is blank.

This worked until until a couple weeks ago.

Here is what we tried, but still didn't resolve the issue

Outlook 2016 - repaired and re-installed.

Adobe Acrobat Reader DC repaired and removed and re-installed

Signed user out of Adobe Sign and signed back in.