Butterfly outdoor example yields wierd results when geometry is changed

Hi Ladybug team,

I've been playing around with the butterfly outdoor example to become more familiar with OpenFoam and its workflow (I'm fairly new to CFD). The example runs fine but the slightest change in the geometry (e.g. changing the size and location of the boxes or adding new ones) returns velocities ranging from 0.0001 to a very large number. The work space is in meters, the mesh seems ok and I have updated the probe grid to match the new geometry. Below I attach my working file. Am I doing anything wrong?

Aris