SSL copy to Webmin went wrong - Button error?

Hi,

I have used LetsEncrypt to create a new SSL certificate which went ok.
After that i wanted to copy the certificate using Server Configuration => Manage SSL Certificate
When copying to ProFTP, Dovecot, etc. everything works fine. However,.. When i push the copy to webmin button, the next screen reports it copied the cert and key succesfully to usermin. After that, the copy to webmin AND the copy to usermin buttons still exist and the cert and key where not copied at all.

Is this a bug in virtualmin/webmin? And how can i fix it?