The Jump spell do not seem to work. I have no points in tumble, and therefor I cant see my tumble score. But if I cast the spell Jump and roll a tumble check I can see that I have 0 points in tumble.
I dont know if the spell will work if I have invested points into tumble.
I believe that you need to have at least 1 point in tumble for the Jump spell to work, at least from my experience of using it.
AllMYbudgies is correct.