Ubuntu – Certificate error when using Citrix Receiver

I am getting this error when attempting to load a Desktop module up within Citrix Receiver:

What I don't understand is I can see this particular certificate is set to "Trust.." under any/all circumstances that I can find. This only happens in Ubuntu, and I did not installed any certificates (manually) on either partition when trying to correct the issue. The browser also appears to be irrelevant (Chrome/Firefox both generate the same error). Forgive my ignorance on certificates, but this seems to be beyond my expertise.

There are a few places I've looked through various search engines, and I found other users who have had similar issues with certificates in the Linux Citrix Receiver, but I'm not sure what's wrong with this certificate, as none of the other suggestions I've tried have worked so far, and they're too numerous to go into detail… so I'd like to take it from here and see what you all can offer up.