I experienced some difficulties after assigning SPICE_LIB_DIR in an attempt to gather all spice models in a global location.
The above image shows that a model (this was the case for all models) that was at the location couls not be found at that location.
This behavior persisted even after manually again selecting the model.
I had SPICE_LIB_DIR assigned as in this image
After deleting the SPICE_LIB_DIR assignement and again putting a spice models folder in the project directory the simulation ran again.