NPC do not want to settle in Obsidian brick house

[Bowmore]

NPC do not want to settle in Obsidian brick house.
Tried with different furniture they agreed on before - no use.

 

[Bowmore]

Nevermind it's not a bug i solved this.

 

[Christopher Anthony]

What was it?????

 

[Bowmore]

It was Crimson being close to the surface. But hard to see.