Hope this could help

[Lascap]

As you can see in the Image 1 bellow, everything looked fine when I was in “Evee” mode".

But when I turned to “Cycles” mode, see what I got on Image 2

In fact, something was wrong in my mesh. I had to go in edit mode on the “wrong” module, select all and use “Merge by Distance” on it (see Image 3).

It removes 4 vertices as you can see on Image 4

And everything went fine after I replaced the wrong module(s) on the house.

[NP5]

Very well problem solved and sorted out.

I take it that module was not a linked duplicate? or more would have been a problem.

Thanks for showing the problem and solution to other students to learn from.