I got some time to play with the radio. In Astro mode the MON button works fine like it did in the legacy Astro series. In analog MDC signaling, MON button has no effect when unmuting is set to AND / OR. But VMUT is working fine in analog.
When receiving an analog PAGE call, the display flashes once and the radio goes back to idle. It will not keep the display flashing and the alert stops.
So this seems like a firmware bug!