sometimes just the “click” does not select and copy all the content …
make sure your certificate and Key are PEM format. If not then convert them using openssl command
The values from Cloudflare should be just saved as .crt (the certificate part) and as .key (the key part). No need to add CA root as a bundle or combine it within - at least I didn’t had to.
If you were adding as a bundle, maybe in the wrong order?
May I also ask what is your output of running openssl version -a and which openssl ?