When trying to authentication to the REST API in production I get an invalid_client error

[MWLamotte]

When switching to production my requests for authentication to "https://api-m.paypal.com/v1/oauth2/token" get the following response:

{"error":"invalid_client","error_description":"Client Authentication failed"}

I have verified that it is using the live client id and secret, and if I just switch back to the sandbox it all works completely fine.