It will not hold it. It would be continually cycling. What do you have the dif set at? Normally You will have a swing in temp whatever it is set at.
But you have it set for cut in right? It should drop below the set poit the dif amount.
What do you have the asd set at?
If it is on the left leg only, it is the same as pulling it off completely. The jumper works as a "piggy tail" connecting the two posts, and shorting across them. With it on one only, it is doing nothing.
If they are only on the left leg, they are "off", not jumping anything. Read Table 2, Jumper position- removed.
It sound like you have everything set correctly, and may have a defective unit.