Solved the issue. The originated method is not async which caused the issue. 
it is working if I change to synchronized
.
Hi @hdu,
It seems you are trying to use sync and async methods together. Could you try the async version of the toList method?
var taskInstanceList = await _taskRunnerInstanceRepository.GetAll().Where(x => x.TaskRunnerId == id).ToListAsync();
Made the changes to your suggestion but it is not working.
