I am working with a colleague who is trying to send a Box Sign form to a user, and every time they do, they get the following message, and I am not sure how to advise.

The placeholder with the UUID a4f7a8d5-3c............" was not found. 

How can I get around this issue? Does it have something to do with their account?  I know the Box Sign form exists, as I just used it.

Thank you for any help you can provide. We're currently stuck.