Error when calling get_pool_full_data on tonstake contract (v3 testnet)

[trevor-crypto]

Using https://testnet.toncenter.com/api/v3/index.html#/api%2Fv2/api_v3_post_v2_rungetmethod

and the request:

{
  "address": "kQANFsYyYn-GSZ4oajUJmboDURZU-udMHf9JxzO4vYM_hFP3",
  "method": "get_pool_full_data",
  "stack": []
}

we are given a 501 response error:

{
  "error": "Unsupported stack parameter type: tuple"
}

This is working on mainnet with the same values (and appropriate addresses).