If you find that the bulk variations grid isn't working, or you can't see the 'Bulk Variations' tab on the Edit Product screen, then this normally means that the variable product is not eligible to use the grid.

The plugin is only designed for variable products which have 1 or 2 attributes which are used for variations. Please see our article 'Which products can have a bulk variations grid?' to make sure the product is suitable to use the grid.