Do you think ivern just lacks power or....

Right now I think he's just too predictable and players haven't optimized him yet.

The bushes could be very powerful if used properly, but people aren't used to the ability yet. They're putting them in hugely suboptimal places. E.g. I played against an Ivern top this morning (had a DC so we lost, but destroyed him in lane despite being camped). He placed bushes in front of his tower to hide in while he tried to last hit. Except once I killed his melees, my melee minions walked in to the bushes and gave me vision of him. Then once I cleared the wave, I had the bushes to hide in and poke him from while he was a sitting duck under tower. I'm pretty sure the bushes could make big plays, but players need to figure out what the best way to use them is.

His stun is a ranged stun, you can't complain about that.

His free dash is only a free dash for melee champions. Get a few good melee champions on your team (e.g. Darius top, Cho'gath/Kennen/Talon/Morde mid, maybe if Ivern is support then a melee jungler as well) and it becomes a hugely useful ability. Throw Ivern with a Quinn top, Ryze mid, Caitlyn ADC, and Morgana support, and the ability is entirely useless. His win rate is going to be garbage if people don't pick around him.

Finally, his ultimate. It's interesting. Definitely weaker than Tibbers, which is a problem since the rest of Annie's kit seems better than his tbh. If his ultimate gave him some stats or dealt more damage or brought some more utility then maybe he'd be in a good spot. It's the only part of his kit where I can see him needing buffs though, and really we need to wait and see what happens once players learn to use his bushes better.

I think his kit is just garbage. It sounds great, but in practical game play other tank jungles are 10x better than Ivern, and other AP junglers are also 10x better than Ivern. He doesn't have enough utility to make up for his lack of damage, and he doesn't have enough damage to make up for his "okay" utility.