Godaddy SSL Wildcard Fail

I bought a GoDaddy Wildcard certificate for our corporate website (with existing website) and our MIAB box.
No matter wich CSR i use to generate the certificate, when i try to install it into MIAB the answer is always

“Error, Something went wrong, sorry.”

See https://github.com/mail-in-a-box/mailinabox/issues/467.