Membership ID in URL not working

Hey there,

We're working on getting our registration working with Membership2 and BuddyPress, but we're running into issues when trying to supply a membership_id in the URL.

The default registration page works fine: including the captcha, but as soon as one of the membership is referenced it doesn't funciton at all anymore:

All I can see is that it adds hidden fields for the membership ID (hidden input with name="membership_id") and that it adds some other hidden fields.

I'm unsure where to go from here, it simply doesn't do anything. No validation either, it just posts to the form otself without doing anything.

It also doesn;t work with the default registration page (currently we're using an altered template to provide for the extra fields from BuddyPress).

There are also no JS errors.

Could you possibly tell me what's going on?