For some reason still unknown to me, AC pulls its alerts from the Events log in SW. I've never noticed to date anything that appears in the alerts or advanced alerts tab to show up in AC, yet if an event of warning or higher goes through the event log, as long as the routing is setup, it goes through AC with no issues. Took me a few weeks of tracking things to find this out. My advice is to see what your Event page is showing and then look to see if those are showing up in Alert Central. If not, you may need to re-configure the connection to Orion in AC again. I've had to do that once to get alerts to show up again after some updates killed the link.
Hope this helps.
JPA