Hello,
Some elements are still pending :
Please provide more details regarding your Stripe Connect configuration and the nature of the error (where & when you got that "Unknown Error").
If you have the credit card elements from Stripe, it means that the JS library is loaded ; but it also means that Stripe API is returning (in JavaScript) an error which is not currently handled by the plugin (so a generic error message is displayed).
Details of your configuration would still help ; and for the rest, it would need to analyse the content returned by the API ; and the way depends on how your plugin is configured.
Regards,