Berserker, unfortunately, the save game was heavily modded, you will have to download stuff in order to load it. I don't think it is worth the time.

So I know clearly how exactly this problem happened. It was resulted by my script of boosting AI turn speed.
The script is long, but the main idea is rather clear: It resets AI heroes every X day with the function !!SN:E5081488/(CALLCONV_THISCALL)/(heroPtr)/(hero); to remove some unimportant data so that the AI could start moving instead of being stuck in a place for minutes. I don't know the details of this function, but it just works. The AI heroes do have a shorter time of responding.

My script:

Full script for download

Here comes the problem of my script:
In most cases, the script works ok. But for some reason, usually, after Month 2, there is a chance the script results in an error just like the screenshot here. Pink player's heroes were moved back to the map, yet the owner could not be set correctly. If this happens, the game will crash the next day when Pink is about to move, but if loading a save game before the day with error and re-execute my script, the error could be gone. That is a say, the problem does not happen 100% but once it happens, it is the end of the game.

Here I'd like to know if you guys have advice on my script or boosting AI turn speed in general, mostly I want to know if there is a chance to fix the issue of missing hero owner by executing this script.