I don’t know where you got it, but a friend had asked me to cut 1/4 inch mdf for her that she got a home depot. I was able to cut through it without issue using the Thick Draftboard proofgrade settings. I feel like depending on where you got in, the MDF could be much denser than other materials despite being the same thickness. Anyways, here is a link to how to test new materials to hopefully help you out: