AWS Transcribe Websocket

I’m trying to use the WebSockets module in Unreal to connect to Transcribe-Streaming. I’m creating a presigned URL and have tested it in Postman and it’s connecting, but in Unreal, the socket returns a message saying: “The Request Signature we calculated doesn’t match the signature you provided…” Since I’m passing the same URL with the same Signature and other parameters in Postman and Unreal I’m wondering what else might be causing this error?