I’ve run into a toolset problem where some ground-trigger-style traps seem to be invisible to my campaign NPCs. I suspect it’s a walkmesh/LOS issue because it only occurs in two places: on a raised elevation using the default rural ruleset, and on the barrow tileset.
Has anyone else run into this problem and is there a solution?
They may be too hight lvl for them to be detected ?
The detect/disarm DCs are well within the NPC’s capacity, so that’s not it. Also, in that case they normally say some version of “I can’t disarm that”. In these situations they just dumbly walk all over the traps and set them off. A pixie familiar does the same, but players can take control of the pixie as a workaround. The henchmen, not so much. 
Are they all the same traps ( working and not working ) like gas, electric, fire etc. ? It might just be an issue with a certain type of trap. If so try sticking down copies of traps that definitely work, make a blueprint first so it’s an exact copy just to be sure.