Here’s the dimensions of mine when I measured it.
Did you try zero-ing with the 1/4 inch 201 cutter and then swapping out for a V bit and manually checking whether it was over the corner of the stock?
Also, are you using the 201 cutter or some other 1/4 inch cutter? I ask because some of the Yonico 1/4 inch cutters I use are low helix 2 flute
and you need to make sure these are at the right angle to contact the edges of the block at their outer dimension. The 201 has 3 flutes and a much steeper helix so it needs limited overlap to ensure the cutter perimiter hits the block.