I have never done coco myself, but I believe the solution grade gypsum works best in coco.
Also, the gypsum flush seems to show best results when using coco.
Coco and calcium have a weird relationship, as you may know.
What a gypsum flush does in coco, to the best of my knowledge anyway is…
It will reset the CEC sites by knocking off unwanted salt and nutes off of them, and add back calcium and other needed elements, this works to rebalance the CEC and helps the proper nutes become available again, especially if anything gets locked out.
I would not say it will fix lockout but it will help prevent it from happening in the first place.