Received the following error first time trying to process real transaction:
"Payment error:We couldn't charge this card because its Stripe token was created with an API key in test mode and now a charge is being attempted with an API key in live mode."
Noticed there was a plugin update, so I just updated. Same issue. From documentation this error only occurs when using the the correct test keys in live mode, so I tried putting the live keys in the test mode boxes and it successfully processed.