I may have also run into this. I did kill a Sebillian with a pair of grenades as shown on Turn 6, in both cases the nearer soldier (Lt. Carol Eriksen) should have been 1 tile outside the blast radius, and didn't suffer any obvious damage from either grenade. Autosave at the start of Turn 6 loads, autosave at end of Turn 6 crashes to desktop.
auto_groundcombat_turn_6_end-466.json
output.log.zip
auto_groundcombat_turn_6_start-465.json