Hmm, not sure about this, perhaps it's a firewall issue?
On the title screen do you see the "2500 pumpkins submitted this year" in the bottom left corner?
I can double check the latest Linux version to make sure it works for me (tbh I don't check it with every patch) but perhaps the Unity log has something helpful in there. I need to remember where it is on Linux tho, I'll get back to you.
Also, have you ever played the game in a previous year and had it work?