The workbenches are 2 x 1 or 2 x 2. Minecraft does not natively support blocks that are bigger than 1 x 1 x 1 (trying to use VoxelShape will end up making the block have unwanted properties. For this it is best to use a "fake block" similarly generated by a bed, this method should be similar to other mods like Immersive's engineer's workbench

First issue :)

Fixed next update