[Closed] Damp bricks, should I remove + how?

I've been investigating a damp issue in an old outhouse converted to a toilet and utility. I have a damp meter, and have removed several courses worth of plaster to let bricks breathe. Had a dehumidifier running for a couple of weeks. All but two bricks seem to dry out. They feel dry to touch but the damp meter says they aren't (other bricks seem OK). These are on an internal dividing wall between the two small rooms rather than an external wall. I am pretty certain the damp is caused by condensation not water ingress. It is very humid with no vents. Solid wall single story construction on the outside of the main house wall.

There is an old lead pipe relatively close by, I've removed the plaster and checked it over, cannot see any evidence of leaks. Wrapped it in kitchen roll to see if it would get wet. Bone dry. The only thing I can think of is there is another pipe in the wall behind the brick, but I cannot see why there would be a pipe there, and there is no evidence of it other than the damp brick.

So should I try to remove one of the bricks to have a look behind? What is the best approach? I have a SDS drill and chisel bits. Or stick with what my gut is telling me and there is nothing there, and there is something up with the damp meter?