For AI ko fights are hard to read.
As a human you simply count the ko threats for each colour.
The AI has to play out all variants for this fight. So it seems reasonable to assume that AIs tend to avoid ko fights.
To read out a ko fight involving 3 ko threats for black and 3 for white, the AI has to read through at least 36 variations with 18 playouts each. The resulting board positions look the same for a human, but for the exploring AI they are 36 different branches (board positions). All 36 branches have the same chance to win (they are the same board position) so the AI has to spend its remaining playouts equaly on all 36 branches.
For LZ with 1600 playous this results in 1600/36-18≈26 playouts per branch.
To read out a ko fight involfing 4 thrats per colour creates 576 branches and needs 1728 playouts (more than LZ has to spent).
A ko threat is a move plus a response which doesn’t really change the win rate for both player (ignoring possible future ko fights), so to play a ko threat immediately could look like the best move on the board. A move can only reduce ones win chance after all and the ko threat doesn’t seem to reduce it.
Besides if the AI explores the ko threat it halves it’s playouts by exploring 2 almost similar board positions (similar by chance to win).
Thinking about it, if its estimated chance to win goes down with each move it reads deeper, to play the ko thread looks better since the effective reading deeph is 2 moves lower.
On the other hand, LZs neuronal net could learn to play kos only if a ko threat is needed (if a ko is active), but it doesn’t seem to care.