Pressure Fluctuations - FDS 6.9.1

[cmckever]

I am running a model of a mechanical extract shaft system in FDS 6.9.1. The results are showing random pressure fluctuations in just one lobby in the model. The extract rate in the lobby is constant (snip below). I haven't seen this issue before, were there changes in FDS 6.9.1 to meshes and how they should connect together?
I have been trying to simplify the meshing but am struggling to find the issue. Thanks in advance!

[drjfloyd]

Try running with the current release.

If that doesn't work please simplify your input as much as possible and attach.