Invitees' permissions status "pending" even after accepting invite

Hi Laura, 

Welcome to Box Community and glad to assist! 

To find and resolve a pending invitation:

1. In the left menu of your Box account window, click All Files.
2. In the pending invitations panel under ACTION REQUIRED, hover on the name of a file or folder.
3. To see details about the invitation, click the ellipses, "...", and select View Details.
4. To decline the invitation, click the ellipses, "...", and select Decline All.
5. To accept the invitation and gain access to the project's content, click Accept.

In reference to this, please see this article.

Thanks for posting!