OpenSSL version for Beats input

I'm trying to secure the Beats input of section with SSL. I followed various tutorials to generate valid certificates, but I always end up with the error OPENSSL_internal:WRONG_VERSION_NUMBER.

I'm using Ubuntu 18.04.2 with OpenSSL 1.1.1 11 Sep 2018. Is this the wrong version for Beats input?

If I try to use pem certificates from certutil I get the error that I need pkcs8 files, once I convert them with OpenSSL I again get the wrong version number error.