40K: No Retreat! combat assault results loophole?

Question

This is a follow on question to Orks Mob Rule in Warhammer 40k. This situation is "No Retreat!" when a fearless unit is defeated in an assault, the fearless unit takes wounds equal to the number their side has lost in combat. I understand so far.

But on p.44 of the WH40K 5th ed rules the last paragraph under "No Retreat!" states:

If none of the enemies involved in the combat against a fearless unit can actually hurt it, the unit does not suffer any wounds if its side is defeated in combat, and simply continues to fight.

If the fearless unit's enemies can't actually hurt the fearless unit, then how did the fearless unit manage to lose the assault in the first place? Are the rules saying any of the fearless unit's enemies still left standing after the assault?

Answer 1

I can imagine a few situations that would trigger this rule.

There are a few special rules that give a unit a +1 to combat resolution. So if the fearless unit whiffs and gets no kills, they can still "loose".

Another situation is if there are two units involved in an assault with a fearless unit, and the one that can hurt the fearless unit is wiped out.

Finally, if the unit that assaulted was able to hurt the fearless unit only by means of Furious Charge's +1 to ST.

There are probably a few other situations. It's defiantly an edge case and I've never seen it come up, and I've been involved in running numerous large(30-60 person) 40K tournaments.