Oh yes, I remember this issue now. The velocity orientation property does not do any interpolation of its own. It just takes the last two positions in time. If those two positions are the same, then there’s no valid orientation that can be discerned.
There’s some discussion here about how you can work around this: The orientation of vehicles has problem when waiting in front of traffic light - #2 by omar by using a CompositePositionProperty that defines how to handle this case in your app.