When a member attempts to submit their information on a Hustle opt-in, the following JS error is generated: https://goo.gl/cU2XiC
Full conflict test has been performed with no improvement. The Hustle error log states the following:
James,firstname.lastname@example.org,FIRST_NAME must be provided - Please enter a value,2017-05-11
As you can see, the first name is provided.
More information, including access, in chat log.