Runners at first and second. Two out. The next batter is out at first.
Runners advanced during the play. Which bases were the LOB Runners considered to be left on? 1st and 2nd, or 2nd and 3rd?
Imagine that the play started with bases loaded. The runner on third does not score, so you'd never consider saying that the inning ended with that runner left at home.
They haven't safely advanced. If it matter for stats, the LOB would be first and second in this scenario. (I'm not used to caring what bases are reached for LOB count).
The answer is it doesn't matter. I understand what you're trying to ask but if there's two outs and the batter doesn't make it to first base nothing else matters or is recorded statistical other then simply 2 left. A runner could literally cross the plate before the batter gets thrown put at first the run doesn't count.