Totems not using skills when attacking with Rolling Magma and "Cannons, Ready!" Tactician node

I am currently using Mortar Cannons with Cluster Grenades socketed inside. The "Cannons, Ready!" Tactician node states, "Totems only use skills when you fire an Attack Projectile." Rolling Magma is an Attack skill with the Projectile tag, so if I use Rolling Magma while I have summoned Mortar Cannons, I would expect the cannons to fire after the Wyvern spits out the projectiles. This is not the case. When attacking with Rolling Magma in an environment with plenty of enemies to target and multiple Mortar Cannons summoned, the Cannons instead do nothing