Error "Not a valid page link format. URL must start with http:// or https://"

When I try to add a Netflix URL to the (streaming) services of a page, I keep getting the error "Not a valid page link format. URL must start with http:// or https://". The URL I'm trying to add does start with "https://". I've added URLs to the services of pages before and this is the first time I've encountered this issue.