Unable to add 'N Box Cell Assignment' section under Talent Ratings from Person Spotlight

Summary

Unable to add 'N Box Cell Assignment' section under Talent Ratings from Person Spotlight - no 'Add' button

Content

Hello!

Managers do not see the 'Add' button under the N Box Cell Assignment section under Talent Ratings in Person Spotlight.

Enabled Edit under content section access for Line Manager custom role and re-generated the roles.

Tried to see if I need to enable the 'Add' button using page composer but couldn't find a way. 

Also, we see the 'Add' button for all the other sections under Talent Ratings. 

We're on responsive UI.

Any help is highly appreciated!

Thanks,

Anu