[Bug] "Signum" doesn't work

[Xilmi]

The ability "Signum" of the Devastator Space Marine supposedely grants +10 ranged accuracy. Thinking "wow, cool, so I can move my Devastators, use signum and then still do full damage", I attempted exactly that.
But nope, moving, and using signum still left me at an accuracy of 2, making the ability essentially useless.

It might be possible that it works without moving as in the order in which the heavy-debuff and signum are applied might be reversed. But in this case it would be a really underwhelming ability given that it has 10 turns cooldown and requires a tech to be researched.

Edit: Nope, it doesn't work even without moving.