Hello did you by any chance have a unit of artillery with them that started the attack but was killed?

I had already answered your bug report before Dante figured it out also

Thank you for your report.

This looks like an artillery unit was recently a part of this I6 group. Even though the artillery unit has been eliminated the attack order continues. At the end of the countdown of one hour from the last artillery bombardment the I6 group will begin forward movement to attack your armored car. Thus no damage can be done from this range when the countdown ends.

Oh, that sure is cool.