Hi,
I did a test by generating a self-signed certificate on a XG and installed it in a SFM (16 beta2 build 20). When I select it on the administration page for Webadmin, SFM notifies that it's OK.
I close the browser and then I reconnect to SFM admin but I can see that the certificate presented is still the default one.
Maybe I miss something but it seems to be a strange behaviour.
Regards.