Using Discourse with Cloudflare: Best Practices

I believe I followed the recommendations (I am using free Cloudflare), and I have 2 issues I see so far:

(1) The main login screen is blank on every first access, if I click on the URL and hit Enter again it appears.

(2) embedded pdf’s break so not visible but still download. I tired bypassing pdf file extensions in a cache rule, to no avail.

Pausing Cloudflare does not help. Neither of these is an issue if I am not using Cloudflare other than for DNS (grey)

Possibly any ideas out there what I need to do to best debug or fix these 2 issues?

Thanks in advance.