Hey Matt,
I'm posting this here as it is the solution to an issue you were helping me with a few weeks ago with. I tried to comment under that ticket, but because my old account expired shortly after seeking help and I have since created a new one, I'm locked out from commenting on the old one.
Anyway, if you recall, I felt like an update from RS Form Pro had broken the plugin as it was returning an error before you could even submit the Stripe card details. After a lot of trial and error comparing your supplied single product form backup, I've figured out the issue.
(see screenshot)
Under the Form Properties -> Form Info -> In the Submission Section. If the "Disable Submit Button On Submission" is set to Yes, It won't allow you to enter card details into the Stripe popup window and automatically forwards you to your set Return URL location featuring the error at the top of the page. Switching this to No fixes it.
My question is can this be fixed? As the reason it was enabled was to cut down on the impatient type who get click happy and submit multiple forms. ;-)
Thanks,
Brandon