Forms stuck on spinning wheel since update to version 5.4

Just updated to the latest version and am having an issue where I just get the spinning wheel when I hit submit but the form does get submitted as I do get notifications. To the user it appears the form is not submitting though. I find the issue most on Firefox and the console error I am getting is that the /contact-form-7/v1/contact-forms/20480/refill?_locale=user file is showing a 404.