Uploading model into shape population viewer taking longer than usual

[Sophrobs]

Hi there,
When uploading VTK models into the Shape Population Viewer 3D slicer becomes unresponsive and takes approx 10 mins to load before I can view and manipulate the models. I have tried using a smaller file (e.g. just mandible compared to entire face) and it doesn't seem to make a difference.
In addition, manipulating the colours and ranges seems to be bugged - it doesn't respond like it did in the past. I cannot add additional points. Any help would be most appreciated.
Thank you!