The Maw

Something seems wrong about The Maw. It seemed like most of the time, it didn’t complete the cast, and any ship caught in it was released unharmed. At first I thought the unit it targeted had died or phase jumped or phased out, but I’ve had this happen other times. When I’m killing a minor faction I’ll park it in front of their ships and then eat them as soon as they turn enemy, and this works like 1/5 times. The last time I tried it it only casted for a split second before it canceled. 

Is this somehow intended behavior and I’m using it wrong? Is no one else frustrated by this ability? Out of curiosity I kept track in my past game. Out of 11 casts, only two finished casting and ate all the ships. Out of the 9 that didn’t finish casting, only two of those managed to kill even one ship. 

So am I missing something? Does the channel time depend on antimatter or something? The tooltip says 20 seconds but I’ve never seen it cast for more than 5-6 before it just stops?

This is with the ability on manual cast. On autocast it’s even worse and never kills anything.