Rewrite rule HTTPS to different port

Remember that when you make an HTTPS connection to https://domain2.org (which is really a connection to https://domain2.org:443), the order is roughly

1. Browser opens connection to IP on port 443
2. Apache looks for a VirtualHost matching the combination IP:443
3. In this case it finds the VirtualHost for domain1.org
4. Apache sends the SSL certificate associated with that VirtualHost (i.e. the cert for domain1.org)
5. [The rest of the SSL negotiation]
6. Browser sends its HTTP request headers, including the Host: header telling Apache what domain it thinks it's talking to.
7. If applicable, mod_rewrite processing of the HTTP request headers happens here.

i.e. when Apache decides which certificate to send, it hasn't yet received the information that mod_rewrite would use to do the redirect.

To get around this you'd need a single certificate that was valid for both domains. This could be either a wildcard certificate (if the situation is domain1.example.com and domain2.example.com, get a certificate for *.example.com), or you could try to get an SSL certificate with a Subject of "domain1.org", but a Subject Alternate Name of "domain2.org".

In either case you'd need to do the redirection in the main Apache config files - if it's in a .htaccess file in domain2.org's DocumentRoot, then requests that use domain1.org's VirtualHost will go to a different DocumentRoot directory, and won't ever see the file.

I would hazard a guess without you posting your ELB configuration that the ELB is redirecting HTTPS (443/tcp) traffic to the EC2 instance on HTTP (80/tcp). Then you're .htaccess and plugin are trying to redirect it back to HTTPS because it is being seen over HTTP.

Go take a look at your EC2 console under Network & Security > Load Balancers and I would imagine you'll see the Port Configuration says something along the lines of 443 forwarding to 80 (HTTPS, Certificate: blah)