Dynamic Stamp issue in Acrobat Pro

Hello - I'm trying to assist a user who uses Dynamic Stamps in Acrobat.  She has several that she uses for different documents, and there is one stamp that has gone missing from her list of stamps when she tries to apply it.  The stamps are being saved under the Adobe folder in C:\Program Files.  The stamp is there, but not showing up like the others.  I've also seen where the stamps are stored in the local user folder - we tried moving it there, but there was no change. Has anyone run across a similar issue and provide some other steps we can take to get the stamp to show up?  Thank you.