Skulk Sensor and TnT dosent work

I was messing around with skulk sensors in the newest snapshot 20w51a, and i tried using a skulk sensor next to a tnt block under the ground, as a sort of landmine, but when i went into survival and activated it, i found i didnt take any damage, then i tried activating tnt with a flint and steel to see if it was tnt that wasnt working or something else but that did damage to me, but then i opened up a new world and i took damage again, then i deleted the second world, and made a third, and then i didnt take damage again