We've played 1 hand before. I opened KKJx UTG and he called my ~pot cbet and insta checked down AQxx on a KJxJx 2tone flop. His sizing is confusing me

PokerStars Pot-Limit Omaha, $0.25 BB (6 handed) - Poker-Stars Converter Tool from FlopTurnRiver.com

MP ($30.20)
Hero (CO) ($30)
Button ($25.50)
SB ($5.80)
BB ($26.50)
UTG ($12.10)

Preflop: Hero is CO with A, J, 9, 10
UTG calls $0.25, MP calls $0.25, Hero bets $1.35, 2 folds, BB raises to $3, 2 folds, Hero calls $1.65

Flop: ($6.60) 3, 2, 8 (2 players)
BB bets $2.75, Hero calls $2.75

Turn: ($12.10) 10 (2 players)
BB bets $6, Hero calls $6

River: ($24.10) J (2 players)
BB bets $14.75 (All-In), Hero ???