I suspect they have few hostages alive and they are most likely in dreadful condition.
Even the proof of life videos-—which they arrogantly refuse to make——would have terrified and hopeless hostages saving the others by lying. Like American POWs who won’t blurt out the truth because other POWs are under threat of death.
And the Qu’uran lets Muslims lie to “the idolators” (Christians and Jews) and “the infidels.” Several times in their phony book.