Widget will only load in one very specific configuration

[otonoton]

Using version 5, I'm having tons of problems getting the upload widget to show up at all, it only seems to work with one very specific configuration. It seems I must be using a class name of exactly "dropdown" (no other value seems to work), and also disable autodiscover and manually creating the Dropzone object.

Using default autodiscover with <form class="dropzone"></form> - "No URL provided." It seems to ignore the form action entirely and refuses to load.

Using default autodiscover with <div class="dropzone"></div> - "No URL provided."

Using new Dropzone("div.dropdown") - "No URL provided." and "Dropzone already attached."

Using Dropzone.autoDiscover = false; new Dropzone("div.my-dropdown") - "No URL provided." (yes I changed the div class name to match)

Using Dropzone.autoDiscover = false; new Dropzone("div.my-dropdown", { url: "/foo" }) - no error but nothing is displayed

Using Dropzone.autoDiscover = false; new Dropzone("div.dropdown") - "No URL provided."

Using Dropzone.autoDiscover = false; new Dropzone("div.dropdown", { url: "/foo" }) - Works... however there is a 2em margin that makes it render outside of the div:

Any idea what is going on??