Sorry, I really can't help with the noise cancellation control algorithm, it's not a field I know about. Now that we got latency out of the way, there's not much more I can offer.
Can you help me? My "Error Mic" gets unstable, instead x+y during the time tend to zero.
Unfortunately I also cannot help you with your ANC algorithm.
I can only suggest (again):
What do you mean by: "Clean up your VI"?
In the LabVIEW help you will find a chapter called "Style guide".
It recommends straight wires, going from left to right…
(That's just a start, there are other things to follow, too.)
The upper DAQmx task reference also should be kept in a shift register. You don't need shift registers for the error wires when you stop the loop on the first error…