Track specific links do not allow the submitter to move past the first page

[marcwalsh]

Current Behavior

When accessing the submission portal through a track link eg: https://pretalx.com/mozfest-2021/cfp?track=410-sustainability the continue button does not forward to user onto the next page, instead, it just refreshes.

Expected Behavior

When using the track-specific link, I'm able to continue past the first page of the proposal form.

Steps to Reproduce

1. Access the submission form using a track-specific link: https://pretalx.com/mozfest-2021/cfp?track=410-sustainability
2. Complete all required fields in the first page
3. Click continue
4. Page refreshes instead of continuing to the next page.

Your Environment

Checked on both FireFox and Safari and this issue is consistent on both browsers.

[marcwalsh]

This isn't an urgent issue for us at the moment, as we've just changed any specific links to the generic link, however I thought I should note it just incase.