iCloud - Access denied

On my OpenHAB 2.10 server, I’m using the iCloud binding to track the location of our iPhones. Today I started seeing authentication errors:
error": { "code": "Unauthorized", "message": "Access denied, please inspect WWW-Authenticate header.", "target": null, "details": [] }

I know that our user accounts didn’t change, does anyone know if anything change on the Apple side?