Many say that bots do not damage bosses AT ALL. I could have sweared that I saw them to do some damage, I it might have been wishful thinking on my part. Not sure any more. 

But stand by the rest of my post: you’re soloing the boss. They need a serious overhaul. 

Maybe they need to keep leveling with you, or just make them smarter and more effective, especially against bosses. And make them use their damn special abilities more often, not only in every leaping year!

Or be able to use your already leveled marines as bots. 

I would also love to select my team of bots, whom to bring along  whom not. Of course this would only make sense, if bots were really useful.  

 bots damage vs mini-bosses - Space Marine 2 (focus-entmt.com)

​I'm almost sure that this is not a nerf but a bug, because bots deal damage to everyone else normally

Yeah hopefully they can fix it.

I made a video recording with a helbrute in vox liberatis (the area before the second elevator where the gene seed can spawn to the right of it in that corner), and the bots did 0 damage. I watched it from afar and the health bar didnt move for 5 whole minutes lol