Anyone know why this is happening and what I can do to fix it?
Hi @uglandkatie
Welcome to the LastPass Community.
My initial thought there would be to try using a different web browser or private window to enter the shared password.
Also make sure there are no spaces accidentally included at the beginning or end of the password entry field.
In some cases specific sites may have different login pages on separate URLs that lead to different access points. Make sure you're using the same web address as your client is using for the login.