I was playing through the campaign with my three wolves, as well as two compagnions (Ignatus and Lapistrix), when I stumbled onto a Keboko.
The Keboko promptly killed all but my Lapistrix, who didn't take damage. (It was the lower front row)
Ensued 15 turns of both of them having the attacking animation but dealing no damage. The combat ended after 20 turns with both of them basically full health.
I tried recording it, as it was quite hilarious, but the twenty turns came and went too quickly for me to do so !
I didn't find the issue on the bug masterlist, hopefully there's no already existing thread on this issue :)