Whenever I restart HA or a power failure occurs and HA starts up again; the manual alarm integration resets itself in a disarmed state. I would expect this to be persistent for obvious reasons 
I have the same issue with the manual_mqtt alarm. I created a NR flow that saves the state to a text file and reloads the state on HASS reboot. But I shouldn’t have had to do that.
I do not have this issue with this integration. From what I remember, it has been solved some times ago.
I have the same issue. not convinced it is fixed.
Weird. Just tried again: activate alarm in away mode, restart HA and alarm is still armed.
Are you sure you are not using manual_mqtt? This one has its state not saved
I have HA 0.107.7 for long time configure manual alarm_control_panel without any problem
Couple days ago I updated to latest HA 0.114.2 then manual alarm_control_panel going to arm_away state after HA restart
I have posted this issue on git