Today I encountered the Tigershark. The spawn-trigger was me eating foods while on ocean in Monsoon-Season. It was passive (as intended) so I decided to go for a fight and lure it to land. But here I encountered my first issue. I hit it with my spear (from ~90% to 0% so about 120 times?) and the Tigershark didn't notice. It was not frozen. When Wildlife (Monster type) spawned it attacked and killed it. But I was just totally unable to aggro or damage it. It was quite a "Cuddleshark". Ending the game and realoding fixed that problem.
Afterwards I lured it at land and put up a fight. When i got the Tigershark to low health (I suppose the threshold when it should retreat) it decided to jump into the water but instead of retreating it re-aggroed but was unable to jump back to land so I could kill it from the coast. It was just sitting there right next to the coast and launching that dive-bomb attack over and over again - and sometimes a bite. (I missed to make a screenshot of that odd behavior.)
As far as I know (from my revealed map) I was not near the shark-kitten den.
I have no mods installed and I'm playing the current shipwrecked beta.
Don't know if this is reproducible but try to spawn a tigershark and lure it to land during monsoon season.