So you get the cutscene of your character putting down the explosives, but after you get control back they don't explode? You should just have a few seconds to move back up the stairs, or at least around the corner, to get out of range.

Are you playing in normal mode or the Developer Mode? Someone who had a problem getting killed in the explosion said they tried enabling god mode, but then the passage didn't get cleared (don't know if that meant the explosives didn't go off at all). In any case, try normal mode if you were in Developer Mode, or vise versa.

You could try reloading a save before placing the explosives and running the game in a window, or something, to see if that would make a difference with the cutscene.

If that doesn't help, email, with a description of the problem; with your save they should be able to fix whatever the problem is, or clear the passage and update the quest.