I've seen it too!  Especially after you've upgraded to the Disintegration Assault level (1rst lvl).  Then it only attacks at the Pulse gun range, but rarely to the shorter Disintegration range. 

It is easily replicated, but it doesn't always do this.  I don't know why it sometimes doesn't move into range.

http://www.filefront.com/14321041/VasSBwontAutoAttack.record

The SB will wipe out everything in the Grav well, but leave 1 extractor untouched!  Later when I've move the SB around, and have dealt a small amount of damage to it, it will turn around and come back to destroy the previously untouched extractor.  I now always issue move orders to my SB, so that it moves across all structures and quickly destroys everything in its path.

http://www.filefront.com/14321059/VasSBwontGoToDisintRange.record

In this replay, a couple different times, the SB will move to attack the frig factory (and scouts & constructors there), but stops short of the disintegrators range, therefore taking much too long to kill them.

Also, I think Debris Vortex is bugged!?  I've never seen it do anything!   No repair, no nothing.  What does it do?

And the 2nd level of Frontal Deflector Sheild blocks 200% of damage rather than 100%?!  How can it block more than 100%? 

1] you need debris. Debris is left by blown up ships or structures, both friend and foe.

2] when you click debris vortex, this scrap metal is being slowly sucked into the middle break of the Orkulus. Once it hits that spot, it instantly heals the Orkulus by some serious HPs.

If you blow, say 20 frigates and then use debris vortex 1/2 in that place, the orky will easily heal by 1500-2000 hit points.

It basically triples the lifespan of a well supported orkulus with 3/4 defensive upgrades done, because either you or your enemy will always be losing ships during a fight, even before the orky begins to need healing. I don't think there is a way to destroy the debris either (auto salvage might mess it up a bit, but it only works on scrapped cap ships). With the help of overseers, the enemy will have to focus on them, otherwise the orky will never go down. With overseers dead, there's debris to heal off.

Yeah, right. Why not remove autoattack from the game completely? When the ship doesn't know what to do, it's easy to fix as well. Just r-click the enemy.

Bah

Who needs autoattack?