Glitches on Isle of Refuge?Follow

Last week I started playing the game, and was going to finish up the razortooth shark quest before going to Qeynos... and I stayed there for hours trying to get the last two sharks, to no avail.
The razortooths were there, but mostly floating on top of the water and when I tried to attack them they said that I couldn't for some reason. Something like 'ineligible target'. My bf said it was more than likely a glitch ? At any rate, I left the IoR for Qeynos without completing the quest...
Was just wondering, what causes this kind of thing and what can I do about it in the future? Does it self-remedy after a while or what?