If the RE is not attacking the squad that you want to use volley fire on, the squad will stay still without shooting through the ability duration.
1-Have 2 enemy squads on range
2-Attack squad A
3-Volley fire squad B
4-RE will sit doing nothing.
PD: weren't you able to use volley fire on the move and change targets as well?
If you move it seems that the suppression is canceled, but there are instances that with only 1 move click the supp is removed but speed penalty and other debuffs remains (for the duration of the ability or till you give another move order)
Added an Issue to our Database, Thanks