Description of the problem

I have a static site published using Pages at a custom domain:

http://persuasiongame.codesimple.net/persuasion/

but, after obtaining and adding a TLS certificate generated with Let's Encrypt, when I visit https://persuasiongame.codesimple.net/persuasion/ it still uses the *.gitlab.io certificate rather than the one I uploaded.

The certificate appears to have been accepted by the Pages custom domain settings which show:

Certificate: /CN=persuasiongame.codesimple.net

next to the custom domain.

Clicking on the "Details" button displays my certificate details as expected.

Any ideas why the certificate isn't getting used?

Which Group/Project (with full path) is experiencing the issue?

/codesimple/persuasion-game

Approximate date/time when the error occurred.

From Aug 17th 2016 ongoing