Sources:
I was having this exact same issue with v1.2.0, and spent some time looking at my IIS set-up and certificates and everything was correct but the redirect kept on happening. What was strange was it worked locally but not on my staging environment.
My solution was to changes the host names set-up in Umbraco.
On my local environment (that worked) I had this set-up in "Manage Host Names":
sub.domain.local/en
But on staging (that wasn't working) I had:
So on staging I change this to:
sub.domain.com/en
This worked! So check your hosts names.
