Round table

Are you saying that the birds simply flew up and didn't attack anyone?

They wanted to attack the Kentaur, but since the cell in front of it was occupied, the birds remained hungry. I think this situation is 100% reproducible with any 2-cell unit against any other 2-cell unit.

Added after 2 hours and 51 minutes
The situation turned out to be more interesting:
So far, I've only been able to reproduce the bug for flying 2-hex units with a native, unmodified speed of 7. Examples: ducks, rocs, cats. I haven't found anything else yet.