export/save 3D mask do not work

[matfallet]

Dear support, I used cellpose-napari on my 3D images (2048x2048x12 slices), only one color (dapi). It works perfectly ! But when I t save the output images (save all layers) with napari, the mask (32 bit) and the outlines are completely black in ImageJ (histogram min and max =0), but the other images are good(flow and cellprob) ? Do you have any explanation or way to export this 3D mask ? Thanks so much. Best, Mathieu