I'm still experiencing this bug, after upgrading to Maverick. I've found that a simple workaround is to minimize, then restore Firefox when this happens - that causes the awesome bar to work correctly again.
I'm thinking this is actually a Compiz problem - it's likely rendering the Firefox main window in front of the awesome-bar popup, causing the awesome-bar history to not be visible.
I'm still experiencing this bug, after upgrading to Maverick. I've found that a simple workaround is to minimize, then restore Firefox when this happens - that causes the awesome bar to work correctly again.
I'm thinking this is actually a Compiz problem - it's likely rendering the Firefox main window in front of the awesome-bar popup, causing the awesome-bar history to not be visible.
It's very annoying. Please fix this ASAP.