I am on Windows 7, Acrobat PRO DC.
I send a document for shared commenting, and my users who are using Acrobat Reader DC cannot comment on the review.
The commenting features are all greyed out and they see this error:
"This document enabled extended features in Adobe Acrobat Reader DC. The document has been changed since it was created and use of extended features is no longer available."
Ever since we upgraded to Acrobat PRO DC this is happening.