I killed the easy cb. He collapsed. 

All attacks stopped at that point. He's dead.

But he's not.

There was no death message and shows that he still has 2k hp left.

This is the second time this has happened to me.

Both times the cb was low hp and needed a brief fight to defeat.

For this same boss the damage I dealt was displayed after the 1st battle as 1 million.

The scorecard showed 982k. That counting error is, imo, significant.