Damp corner in the basement: Transition between waterproof concrete and KS interior wall

Hello, I need advice on the following problem: After the screed was laid in the basement, the KS interior wall in the area of the entrance bay at the transition to the WU exterior wall was extremely damp and dried only slowly. (Over nearly 6 weeks) In the end, only a narrow, damp strip near the floor was visible. However, our heat pump has now been running in the heating program for a little over a week, and the moisture is still visible and noticeable. Is this a defect, or can moisture remain in certain places for that long?

Thanks for the support and best regards, Sven

Can last this long if the area is poorly ventilated.

Such corners really dry very poorly. You could sand them a bit, because a sinter layer forms there, which traps moisture even more after a certain time. If you sand it off, it will dry faster. Give it a try. Karsten