I never really noticed this since I rarely used mortar, but I noticed last night that if you have mortar down you are not going to get grenade resupplied. Unless you have one in hand to prioritize resupply, the resupply counter gets locked in for mortar's nerfed resupply time.
In short, currently if you use mortar, you cannot get grenade resupplied.
In short, currently if you use mortar, you cannot get grenade resupplied.