"Invalid Key" when authenticating from admin dashboard when deployed separately from API service

[itsbrianburton]

I have deployed Medusa by separating the admin app and the backend API service into two separate containers. When I attempt to authenticate through the admin it's responding with "Invalid key."

I have confirmed that it is not a communication issue between the app and the API service.

If I enter an email address of a non-existent user it correctly returns the error: "Invalid email or password"

If I enter an email address of an existing admin user, with any password including the correct one, it returns the error: "Invalid Key"

Locally when coupled with the backend it works fine, but when they're separated it's returning the "Invalid Key" error both locally and when deployed. I'm 90% certain I'm missing an environment variable or some other configuration setting, so if anyone has any idea please share.

curl -X POST https://medusa.example/auth/user/emailpass -H "Content-Type: application/json" -d '{"email": "[email protected]","password": "validpassword"}'
{"type":"unauthorized","message":"Invalid key"}