No active server processes showing despite Process running and healthy

I'm using Amazon Gamelift Anywhere to run a server from my local machine attached to a custom location inside a fleet. My server is running fine, it calls InitSDK() and successfully connects to the websocket. I can see that ProcessReady() has returned successfully and my process is reporting as healthy.

However, the Gamelift dashboard keeps showing that my location has 0 active server processes, and when I try to create a game session using the API, I get this error:

An error occurred (FleetCapacityExceededException) when calling the CreateGameSession operation: Unable to reserve a process(No active and available server processes found on the fleet).

How do I get Gamelift to recognize the active server process I'm running locally? I'm already calling InitSDK() and ProcessRunning().