How many were killed in action and there’s no record of it ?
Gee, I don't know. Given the reflections from my era in the US Army, we still have some few MIAs from Vietnam. Your question will likely never be answered for anyone on any side.
Ukrainian military leaders order soldiers to hold positions until they are encircled and then tell them to keep holding. The soldiers have to decide whether to surrender against orders or die. Military experts have been trying to figure why they do this for several years now.