I am trying to use Zapier w/ ConvertKit to get subscriber notifications. I've connected the apps using the API Secret (*not* the API key) and the apps connect and test successfully. The test email works and is able to fetch my data from CK. However, when I try to turn on the zap for real, I still get the error "The API Secret you supplied is invalid. Try to reauthorize" (and this continues after I re-authorize). How do I fix this?