When I load a saved file it opens fine but my viewport does not show any geometry. I can see the geometry nodes and when I select them the transform handles appear where the geometry should be but it is not viewable. Is there a refresh button that I can press to fix this?

I am running Houdini 11 apprentice

MAC OSX 6 Lepard

Model Name: Mac Pro
Model Identifier: MacPro4,1
Processor Name: Quad-Core Intel Xeon
Processor Speed: 2.66 GHz
Number Of Processors: 1
Total Number Of Cores: 4
L2 Cache (per core): 256 KB
L3 Cache: 8 MB
Memory: 6 GB

Graphics card : NVIDIA GeForce GT 120