Err... you could legitimately get that result, of 1 intelligence at 200 juice, if your hacker squad is composed of 56 small children with extremely low (like 1) base intelligence.
Otherwise, their base intelligence must be -negative-, which shouldn't occur normally. Were you doing some save editing?
No, the last time I edited anything was when I tried to make a little mod a few versions ago. If the information help their not children, the hackers, their all monsters.
They're monsters? Well, that explains it then; both why their intelligence isn't increasing, and why it's so low for all of them. Guard dogs and genetic monsters have a maximum base intelligence of 1, and they're never spawned older than 7 or 8 years old. They have a large penalty to intelligence imposed by their age, which is overwhelming the benefit they would be getting from juice; the juice benefit is actually being tacked onto a
negative intelligence score.
In time, your army of flaming rabbits and warped bears will grow old enough to let the benefits of juice start to show. They'll never be geniuses due to their extremely low base intelligence, but with 200 juice they'll be able to reach 3 intelligence once they hit 11 years old, or 4 intelligence at 16 years old. Or you can send them out to kill some Conservatives; even at their current age they should hit 2 intelligence at 500 juice and 3 intelligence at 1000.
All things considered though, you have built an army of hackers based on the worst possible creature in the game.
Note to self: Animals should probably ignore the effects of age. They have artificially reduced strength, health, intelligence, and wisdom, with artificially increased heart, simply because they're being treated like children.