>20DF07=000008.L

I think this could be just a feature of Hijack: when the final press of a translated sequence is .L, then hijack doesn't "release" that button until you release the real one.. So if you hold the button down too long, the player will just ignore it when the release finally comes (a "feature" of the player for some buttons).

To force the behaviour I think you want, try this instead:

>20df07=000008.L,ffffff

Cheers