I have 3 (more or less identical) domains that i setup on Cloudflare. They all appear to be active in the dashboard: RLPTKT dot COM , RLPTKT dot ORG and RLPTKT dot NET.
I noticed that some (but not all!) test emails sent to a forward defined on the RLPTKT dot COM domain failed. I poked around and found that DNS records were not available on many public DNS resolvers (but were available on others). I’ve never seen behaviour like this before.
If i go to DNSCHECKER, the .ORG and .NET domains are all green checkmarks. the .COM domain is mostly Red X’s.
You need to disable DNSSEC at the registrar otherwise propagation will never complete. Once propagation is complete you can enable DNSSEC via the Cloudflare dashboard.