I just tested 12.50 on CentOS 6 and I could use
call "*plus/web/request","https://tls-v1-2.badssl.com:1012/","",result$,rhdr$
The rhdr$ result indicates it connected successfully via TLS 1.2.
Maybe the looking at the error message from the OS will help. When you get the error do a
print MSG(-1)