[V10.2 - Ground Combat] - grenade deselects after mousing over an enemy

Every time I try to use a grenade and aim directly at the enemy suddenly the grenade is no longer selected and I just see the tooltip (right word?) that shows up if I had the mouse over the alien without having anything else selected.

After that I have to click on the grenade button again to use a grenade.

If I aim at the ground in front of the alien everything works fine though.

regards

Davoren