Can't select "Category" when creating a listing

I’m trying to test the “Free Basic Listing” and “Premium Listing Package” I created. When you select either option, step “3” of creating the listing asks to select a category. You’ll see in that step I created a “test category 1” category.

When I try to create a listing, everything seems to work except I can’t check the box to select that category. When I hover over the box to check it, I get a red circle with a line through it indicating I am not allowed to check the box. I’ve tried it in Firefox, Chrome, and IE, with the same results in each browser.

I also have a local install of wp and the dealer theme on my laptop, and doing it in the local environment, I’m able to select the category and get a listing posted.

Wondering if there’s something that needs to be changed at my host, since it works on my local install? I’m hosting at AWS.

Here’s a link:
https://ec2-54-172-221-91.compute-1.amazonaws.com/add-listing/

Thank you!