Well, i think i may have found the problem but not the solution (it seems really like a bug, keep reading). I tried in skirmish mode. It was in the 1st turn of the game so the problem cant be because of morality i suppose. You pick up a soldier and then you choose some units for reservation (its the butom for reservation, not the one for reaction fire). Then you click ok. Now, you will see that under the TU bar you will have something saying that you have units for reservation. For example, 8 (for a snap shot, whatever).
Now, go back again to the reservation window and choose "no reservation" and click ok, and then you will see that there is a bug, because the text saying that you have some units for reservation (in the example, the 8 will not disapear. Also you will see that in fact you cant do so many thing because of these "ghost" units.
Please, see if i am correct in my problem. If this is a bug, my advice for players (until the bug is solved) is to not choose nothing for reservation.
EDIT: sorry moderators, i had to edit because the number 8, in the original post transformed into a
for no reason lol.