I have the same problem, i follow a similar thread here in the froums since yesterday and there have been some Hotfixes regarding a AI problem. With Hotfix 5 i still have this problem.
Edit:
I should mention that i don't use any mods and started a new profil.
I also own the original game and it's up to date.
For me it seems that some BOT's spawn underground/under the map.
The BOT's above the ground start shooting at them like crazy and spinning around on the spot.
When you shoot at them they ignore you most of the time, it's funny but i guess it shouldn't be like that. xD
In the server Terminal i can see some anomaly that looks like that:
