Domain Mapping Won't Save as HTTPS with WWW Subdomain

Hi - running in to an issue with domains mapped using a WWW subdomain. If they were previously set to http, changing them to https does not save. It just continues to revert back to http.

We have figured out SSL now for our front end using CloudFlare and our users are starting to set that up on their domains - but many use a www subdomain that was previously set to http, and can not get them to save. I saw this mentioned here a while back but there was no fix given.

Any ideas? Thanks