Luxcore - weird stuff with bumps

Some weird stuff going on with the bump, here. The board has a bump texture driven with the brick texture at a straight forward black mortar, white bricks, but the tiles are all over the place, with some weird shadowing around the edges of each tile.

I was just playing and didn’t save the blend. Even so, the tiles should be raised, and the mortar depressed. Ideas?

EDIT: And don’t get me started on the white hints on the shadow catcher.

I’ve barely touched Luxcore, I’ve just started messing around with it. But the “why” is really hard to guess without seeing the nodes and try it out. Remake the board and share it, incl textures that makes a difference, pieces don’t matter. My first suspect is the amount of bump. Or the mapping. From what I can see, the mortar goes in from one corner rather than being tile centric. So a checker and brick would need different mappings, one slightly offset from the other. I.e. if I use mortar size 100mm, the checker would have to be offset 50mm to end up in the middle of the mortar.