Ok, so there was an issue with the threesomes getting stuck because some image issue. I don't quite remember the specifics and would have been fixed earlier that the patch. There's nothing in the patch that would have affected threesomes.
In addition, there's nothing special with the z4 level. In fact, I would guess that about half the images I create don't have a z4 image. There's no requirement for all z values to be represented. As long as you have a z9 or above and the rest have a few different z-values (i.e. don't have 8 z1 for example) it's fine. Normally the code either calls for an image based on the pose (i.e. casual,fun, strip1, nude, etc.) or wants a pose with a higher z level than the current one. In the later case, if you are in underwear at z3, and want a higher one, and there's no z4, it will look for z5, then z6, etc.
So I don't think that's the issue. You are saying that you created these images? What are the file names? My guess is either you have a typo in a file name (or are missing a required one) or there's unexpected hierarchy issue. For example if you have a z4-tl image and then a z5-uw that could cause problems. That's not documented anywhere and I haven't put in code to check with it, but if the z values are out of the standard order I could see something like what you are describing happening.
(As for pregnant images, there's not many of them and the undressing process is not properly accounting for it. I have a fix, not yet published to prevent headliners and contestants in amateur contests from being pregnant. I have special code to deal with it in the standard sex scenes, but not sure about the threesomes, so I may need to prevent pregnant women there too.
Like I said, there's the small chance that they got a job offer because another club owner asked them interview. In that case, unhappiness is not a factor and the bouncers can't get wind of it. Now there's no guarantee that the bouncers will catch every instance either, it depends on their skill. And it's also possible that if the employee doesn't like to complain they may not have warned you that they were unhappy. So it's not perfect.
To be clear there's absolutely no cheating by the AI to make it easier on it to take your employees. If that happened is because of some combination of:
* the employee likes the new owner more than you (i.e. opinion of each owner)
* the employee likes the new club more than yours (distance from their home, friends/family that work in the other club, fame, amount of debt and amount of maintenance are all factors)
* the employee likes the new job more than yours (i.e. worked as a waitress for you and got offered a stripper position and likes sex work more than service work)
* the new job pays more than you were paying (the higher their greed the bigger factor this is)
