Could not establish trust relationship for the SSL/TLS secure channel (self-signed certificate)

I have just upgraded an on-prem client to DW7.7 in preparation for a migration to DW Cloud. I am using a self-signed certificate since this server will only be online for a matter of days. When attempting to export file cabinet settings I get an Oops! 500 error that says "Could not establish trust relationship for the SSL/TLS secure channel with authority '<servername>' ". I have tried importing the certificate into the Trusted Root Certification Authorities on both Chrome and Firefox but to no avail. Any further suggestions?

Dear Mark Young! It looks like the Community cannot answer your question. That's why we have opened a Support Request with the Number SR-198314-N2J2X for you. A Software Support Specialist will contact you directly to follow up. We will update this thread with the solution as soon as we have resolved the Support Request. With best regards, DocuWare Support Team