Can not create a unix socket with imuxsock configuration in rsyslog.conf

Issue

• I'm using imuxsock to create a unix socket to listen on the message from other application.
• I expected that the unix socket was created on starting rsyslogd, but it failed with:

Jan 1 00:00:00 hostname rsyslogd: cannot create '/test/mylog.socket': Permission denied

• /test has a proper permission. I cannot disable SELinux for testing.
• I want to know the root cause.