If you use a variable in an ability, the ability will take a frame longer than it should to execute.
If you remove the variable in the custom block it only takes 1 frame. With the variable in, it should execute on the same frame as the wait block, but it doesn’t seem to. (or an extra frame is added somewhere)
Having just 1 variable block is enough to have this effect, multiple variable blocks are the same as just 1. Also, when the ability is only variable blocks, it still takes 2 frames.