Neutral Bar Isolated

This is considered a sub-panel since the meter and the main disconnect are 6 feet away from this interior panel. My question is shouldn’t this jumper bar be put in place to connect the neutrals on the right side buss bar to the neutral entrance cable? The right buss bar looks isolated but what is strange is no outlets test for an open neutral and it passed inspection less than a year ago.

That is a plug-on neutral panel. The connector for the two neutral bars is visible just below the main circuit breaker.

If that’s true what is the purpose of the the tie bar in my hand?