Hi, this post is getting some attention and I took the time to have a look at the spot in our app FlopHero, where it's easy to visualize the preflop ranges for each player.
First, the setup. This hand is in GG PLO25 with 100bb effective stacks, the rake at this level is somewhat similar to the Rush&Cash games which we currently support, 3bb/100.
Your opponent's 3bet is correct, his hand is a good 3bet bluff and is not strong enough to coldcall with so many players behind and the high rake.
The problem arises with your 4bet, as other pointed out your hand is not good enough to 4bet and the only combos the solver uses with AK as their top 2 cards is the good medium rundowns, but the EV is negative for them.
Let me breakdown what's the 4betting range and frequencies of an UTG open raiser in our solver. As the rake paid is getting higher, the more combos into the 4bet and less in the call to the 3bet the solver chooses, but we see that is always somewhat between 18 to 22% of 4bet.
If UTG opens around a 15-17% (or 40k to 46k combos), then we have that roughly between 8.000 and 9.000 combos should be in the 4bet.
The problem is that any combos with AA are always in the raise first in, but also always in the 4bet range, which comprises exactly 6.960 combos (AAAA is a fold), no matter what rake structure we are in. So that's between 77% to 87% of AAxx in the total 4betting range of an UTG player.
The rest of the 4bet range is usually the best double suited hands that contains an Ace, blocking the 5bet range of our opponent. You were right on that, but you should use cards with less dominated rundowns like AJxx and ATxx
You can check yourself for free here:
https://app.flophero.com/omaha/strat...s=&boardCards=