No longer working

The plugin worked initially but no longer. When I add a model and click save, the model doesn’t attach and the field is blank on the backend. The included link is a product that does have a model. I tried using the same model on other products to see if the size of the file was the issue but it still didn’t work.
I have done troubleshooting by deactivating all plugins except for Woocommerce and the issue persists.

Thanks for your help.

The page I need help with: [log in to see the link]