oauth/token endpoint says my client id is invalid, but it matches exactly what I have in console

Endpoint: https://platform.ringcentral.com/restapi/oauth/token

When I call this endpoint, I get the following error:

{
	"error": "invalid_client",
	"error_description": "Invalid client: {{my_client_id}}",
	"errors": [
		{
			"errorCode": "OAU-153",
			"message": "Invalid client: {{my_client_id}}",
			"parameters": [
				{
					"parameterName": "client_id",
					"parameterValue": "{{my_client_id}}"
				}
			]
		}
	]
}

When I switch back to using the sandbox environment endpoint (https://platform.devtest.ringcentral.com/restapi/oauth/token) everything works perfectly.

I know I have different credentials for both the production and sandbox environments.

I took my Client ID & Client Secret for my Production Environment and base64 encoded them in the format {{client_id}}:{{client_secret}} from https://www.base64decode.org.

These are the same exact steps that worked successfully for me in the sandbox environment but it says my client id is invalid in production... I did a string comparison for the {{my_client_id}} value returned in the error response above and compared it to my Production Environment Client ID in the web console and they match exactly, so I am not sure what to do at this point.

I thought that it was maybe because I am trying to access this production environment endpoint shortly after graduating my app to production, but after a few hours, it still does not work.