12.4XJ as of today is only 12.4(11)XJ1 or XJ2.
Also tried with 12.4(11)T, same result.
Does it work for you ?
I quickly tested your setup in my lab and it works fine. I don't know if there's a 'additional blank space' or 'space missing' in your autocommand syntax. Try removing the config and reentering it.
username test nopassword
username test autocommand telnet 172.30.1.11 /source loopback123
Trying 172.30.1.12 ... Open
User Access Verification
Trying 172.30.1.11 ... Open
Password required, but none set
[Connection to 172.30.1.11 closed by foreign host]
[Connection to 172.30.1.12 closed by foreign host]