/transaction/cost "unknown error, code: 12: cast to i64 error"

[gfusee]

I'm trying to simulate a swap on xExchange devnet with the following request:

URL: https://devnet-gateway.multiversx.com/transaction/cost
Method: POST
Header: "Content-Type: application/json"
Body:

{
"nonce": 229,
"value": "0",
"receiver": "erd1qqqqqqqqqqqqqpgqtqfhy99su9xzjjrq59kpzpp25udtc9eq0n4sr90ax6",
"sender": "erd16awnjdvtxxfdfttk2sd8wyc8nj8fn2yq8crd7drvmve9l2g8hkrsx3g2yu",
"gasPrice": 1000000000,
"gasLimit": 600000000,
"data": "RVNEVFRyYW5zZmVyQDU3NDU0NzRjNDQyZDYxMzIzODYzMzUzOUAwZGUwYjZiM2E3NjQwMDAwQDczNzc2MTcwNTQ2ZjZiNjU2ZTczNDY2OTc4NjU2NDQ5NmU3MDc1NzRANTU1MzQ0NDMyZDMzMzUzMDYzMzQ2NUAwMmZhZjA4MA==",
"chainId": "D",
"version": 1
}

But I get the following error:

{"data":{"txGasUnits":0,"returnMessage":"unknown error, code: 12: cast to i64 error","smartContractResults":{}},"error":"","code":"successful"}