It will only work if its a destrucible or you use a walkable pathing blocker thingy. For the first, select a ramp, copy-paste it and then edit it to suit your needs of a wall, and BAM its walkable. Of course, you must then put pathing blockers around it so people cant through it to the other side. Otherwise, if you want to keep your doodad, you can put it there, put pathing blockers around it, but put invisible ramps on it (i think thats what they are called?) and raise them up to the height you require.