C# ASP.NET Core Web API: How to maintain context in the controller between calling different methods

C# ASP.NET Core Web API: general newbie question. Trying to implement basic Asynchronous Request-Reply Pattern. Basic idea is that:

1. Client calls POST {url}/DataProcessor/DataX with some payload
2. Client checks on the status of the transaction using GET {url}/DataProcessor/DataXStatus, until HTTP Status Code of 200 is returned
3. Client gets xActionId from the response above and then calls GET {url}/DataProcessor/GetResults/{xActionId} to retrieve results of data processing.

This is what my controller looks like: When I call DataXStatus method (after properly calling the DataX method), the _processData isn't in the right state, like it has gone out of scope after DataX method is done. What am I doing wrong? Is DataProcessorController object gone after any one method is complete? What is the right way to do this?

Thanks in advance

[Route("[controller]")]
[ApiController]
public class DataProcessorController : ControllerBase
{
    private ProcessData _processData = new ProcessData() ;

    [HttpPost]
    [Route("DataX")]
    public IActionResult DataX([FromBody] xData value)
    {
        _processData.CalculateResult(value);
        return Accepted();
    }

    [HttpGet]
    [Route("DataXStatus")]
    public IActionResult DataXStatus()
    {
        if(_processData.IsRunning())
        {
            return Accepted();
        }
        return Ok(new xDataStatus(){id = _processData.GetxActionId()});
    }

    [HttpGet]
    [Route("GetResults/{xActionId}")]
    public IActionResult GetResults(string xActionId)
    {
        return Ok(new xDataResults(){resX = _processData.GetResults()});
    }
}