Can't Blow Up Cave In?

[FKBlink182]

First I set down a bomb next to the cave in, exploded it, and it went down to 12 hp. I have two more left and I repeat the previous steps, set down the bomb, wait for the gnomes to run away, then blow it up. But my two bombs do NOTHING to it. I've reloaded a few times and it's the same outcome every time. There is an explosion but 0 damage is done to the cave in. Any help would be appreciated!

[Super Cosmic Space Magnet]

Can you please take a few screenshots? It might be something weird like part of an object invisibly counting as blocking the explosion (since it doesn't go through walls). Also only the Force Damage will be able to hurt the cave-in (or a really big hammer), if you're using fire oil type things it won't work.

[ffjo23]

You can also attack the cave in with a 2hand hammer. Worked every time for me.

[Brian_the_Brute]

The cave in for Nere should take 2 smoke powder satchels, or 1 rune powder vial both can be found on the other side of the canal where the boat came in. It also would take just 1 smoke powder barrel, which you could have stolen from the Zhent in their hideout.

The cave in where the Rothe are can be cleared by them if you befriend them and convince them to attack the duegar.

[RhiTheWitch]

Try any type of force/thunder damage