Weird Locust Ability problem

[colinjames12]

I have this system in my map. This system is called the pet system. In this system, there will be a dummy unit(pet) which has the locust and invulnerable ability. This unit is inside an item. So when the pet item is acquired, the pet unit appears and if the item is removed, the pet unit will disappear. The pet has a certain skill which can be used within the item ability. My problem is, there are certain times that when the ability is used(the pet ability is triggered), the locust sometimes disappears from the unit.
So the main question is, are there events that removes the locust ability from a certain unit? I know you can't do that in triggers but I'm not sure why this happens.

 

[defskull]

Hmmm, what ability does the pet triggers ?
Perhaps some morphing-based abilities ?

 

[Krogoth]

In this system, there will be a dummy unit(pet) which has the locust and invulnerable ability.

Is not locust invulnerable automatically?

 

[Frotty]

Yea you don't need invul.
But more important, the only way to remove locust is by morphing or hide/remove/show
So just look where you find that

 

[colinjames12]

Thank you Frotty. I did some hiding of units with locust ability and that could have been the cause of it. I also gave the unit with invul just to make sure. I'm not gonna remove it, I have too many dummy units with locust and invul.