I play Minecraft Java Version 15.1.1 on a good-specs PC. I've been trying to figure out how to use command blocks but I don't know what keeps going wrong. I'm putting the Command Block well and good on the ground, I've used all kinds of levers, buttons, pressure plates to activate it.
I was trying to build a house and when I activate it, it just summons a column of sand blocks for about 5 secs then stops.