This Sub Domain tracking.hostyummy.com Works Fine

So does masterclass.workshopsunlimitedllc.com

AND http://tracking.blixbysupport.com

The ones where the LetsEncrypt SSL
is activated do not work.

i.e.
plrstore.blixby.com
powersellertools.blixby.com
info.blixby.com 

And here's a screen shot of my BlixBy.com DNS/"A" Record setup/management page
on Godaddy.com just in case.