Guild banners issue with mobs

Guild banners if summoned like in Teq event or even in WvW are being attacked by mobs/npc and destroyed.This wasn't something that was happening before and it gets destroyed before the timer on it runs out.Its twice i seen it happen now. Once in Teq where the mobs went straight for a hero banner just near the turrets and destroyed it.Second was when we flipped a tower in WvW, the enemy had banners there. The npc started attacking the banners and destroyed it.Just to let you know the Teq one was a freshly summoned banner after the event started so it didn't expire on its own.

This has been happening for a long time. The earliest I've known about it was way back when I used to do the chak gerent event. As a result of this behavior people started spawning the banner in the ogre lane near the ley line run adventure instead of down on the floor.

I wonder if it's only some types of the g-banner. In other threads, we've discussed how some persist for longer periods, some disappear after the donator leaves the map, one has a time limit. (There's not much good research about it, since it's expensive to summon them and wait and wait and wait.)