GitLab Pages is incompatible with Cloudflare SSL certificates

I've recently tried help a prospect to setup GitLab pages with Cloudflare according to an older blog post.

When looking at it with the prospect, we noticed similar effects to what has been described in the comments below the blog:

Using Let's Encrypt doesn't work (probably because CloudFlare doesn't forward the Let's Encrypt ACME protocol requests for the HTTP challenge), and uploading a Cloudflare origin to gitlab with their root certificate is rejected (as somebody indicated in the comments too).

Now I wonder whether we have a new way to achieve this and could amend the blog posting, as it seems some people are interested in this type of setup.