Hustle - Something Went Wrong - Mailchimp, seemingly random?

So, unfortunately, I have also been hit with the something went wrong bug. I am using a single slide-in with MailChimp integration. I have tried the following:

Sign Up Form Tags = Field Names
Subscribers are allowed to use the form even with already subscribed
No other form plugins enabled

Whenever I test the slide-in, I can successfully subscribe without any problems on both desktop and mobile. However, my client and her subscribers are constantly failing and running into problems. They see nothing but "Something went wrong" over and over. I cannot recreate this bug if my life depended on it and at this point, it's a huge headache. The whole launch campaign is being impacted and I cannot figure out why this is happening! Please take a look, thank you so much.