10K units killed is actually 10k OD, I got the award by getting 10K ODT first not by killing 10000 different units like attacker of the day award where every troop you kill counts as one.
I thought it was units killed so popped a ticket in and the reply thought the same. But looking at your current ODT score unless you only killed axes and scouts you would have had heaps more so I stand corrected and your award is for the 10k odt. Who knew (well you obviously)
Will update now and apologies for not knowing this.