I'm experiencing this bug too, I started the game on 1.5.7 and then switched to 1.5.8. Initially, I was recruiting prisoners normally but after some time I noticed prisoners were taking dang long without a single recruit. so I ransomed all prisoners and captured like 10 prisoners around tier 3. time passed and not a single retruit too. so I dismissed all prisoners and captured 10 tier1 looters, and they arent recruitable either.
I kept playing yesterday and earlier today, without knowing if it was a bug or just that it got harder to recruit. However, just now I noticed that when I mouse over the tier 1 looters, the tooltip says tier 4. I moved all looters to the dismiss tab and moved them back to the party, and the tooltip showed tier 1 again. After another fight, I checked the prisoners again and the tier 1 looters' tooltip now says tier 3. So it's definitely bugged.
Not sure if related, but I''ve been investing in steward and roguery skills that affect troops / prisoners. It could be that one of the perks triggered the bug.
PS: I uploaded the save file with the bug description.
Thanks.
