Customizr is great, and I had no problems with the forms, including this one, until the move to 3.0.4
All of the rest of my forms are fine, but this one, to be found on the page: https://uktoremet.org.uk/open-a-ukt-charity-account/
This one now works because I disabled the conditional logic on the form button, to be found in the form settings.
Conditional logic within the form seems to be fine, just the form button CL seems to disable the form.
As I said, others have had similar problems with other themes and suggested the solution I put above.
Does that help?