Alarm_control_panel: mqtt alarm retain flag?

Hello

I have started to use the alarm_control_panel mqtt version which works well for what I am needing. If I reboot HA it reset the alarm as the retain flag isn’t being set. I have searched and it looks like there used to be a setting “retain: true” but it no longer works.

Am I missing something please? on v 98.2

Cheers
Mark