OP, what is the value of
deterministicValue that you used for this line?
if (secp256k1_musig_nonce_gen(
Secp256k1::context().get(), &secp256k1MusigSecretNonce,
&secp256k1MusigPublicNonce, deterministicValue, nullptr,
&secp256k1PublicKey, message, nullptr, nullptr) == 0) {
throw std::runtime_error{"failed to generate nonces"};
}