Is GET /teammate_groups supposed to return an empty list?

I am setting up an integration and using the teammate groups API.

I can successfully create a teammate group and fetch it by id:

• POST /teammate_groups returns 201 with an id like cir_xxx

• GET /teammate_groups/cir_xxx returns the full group object

But when I call:

GET https://api2.frontapp.com/teammate_groups Authorization: Bearer <token> Accept: application/json

I always get:

{ "_links": { "self": "https://api2.frontapp.com/teammate_groups" }, "_results": [] }

Same behavior if I use the company host https://company.api.frontapp.com.

The same admin token is used for create, get by id, and list, and other endpoints like GET /teams work fine.

Am I missing something about how GET /teammate_groups works, or is this a bug with the listing endpoint? Any help would be appreciated.