Why is the website showing an uploaded existing model as missing?

So I uploaded a model onto my profile and it worked for a couple of days. My friend asked about the model so I sent him a link but he says he can't open it. I tried the link myself on another browser and it shows that the model is missing/sorry that page doesn't exist. Yet it is still available on my profile. Why is this happening and how can I resolve this?
Here's the link: Plate Heat Exchanger