BB 8900 simulator - locations won't clear from map

Question

I'm writing an app that has a fairly standard use of maps -- I show the user a list of locations, user picks one, and I display a map with 2 pins (user location and chosen location). Works fine the first time, but subsequent attempts always show the same map with the same pins. The problem appears in the 5.0.0.334 (9550) simulator. I'm invoking the map with:

Invoke.invokeApplication(Invoke.APP_TYPE_MAPS, new MapsArguments(MapsArguments.ARG_LOCATION_DOCUMENT, locationDoc);

where locationDoc looks like this:

<lbs clear='ALL' id='foo'>
<getRoute>
<location lat='3596571' lon='-7880428' label='You are here' description='blah blah'/>
<location lat='3577889' lon='-7880028' label='somewhere else' description='blah blah'/>
</getRoute>
</lbs>

I've verified that locationDoc is being updated correctly every time it is passed to the invoker, but the map never changes. I've tried a bunch of different values for the clear attribute, but the behavior never changes. Is this just a simulator bug? The same code works perfectly on several Curve simulators and a Bold simulator.

Thanks in advance for any insights...

EDIT: If I click on the "Clear Map" menu item while the map is displayed, I see the correct locations the next time the map is invoked. But it only works if I clear the map every time. Surely this is not expected behavior?