Tiles loose under stair supports

Here is now a photo of the support of the staircase on the tiles. Is this sufficient in combination with the other picture?

Somehow it didn't work. Here is the picture now.

Hello Matthias,
unfortunately your picture does not help. Are you sure that the staircase rests ON the tiles and the fleece is not lying around the staircase?
Can you post a picture of the transition between the stair post/tile?

Our steel stringer staircase was even mounted directly on the floor slab, so before the screed was applied to the floor.

Hello Jochen,

yes, definitely. The architect had us hire the stair builder only after the tiler. So all the tiles were already finished when the stairs arrived.

I don’t have a photo like that now. But everything is really on the tiles.

Regards
Matthias

Then I'm surprised that the tiles have lasted so long. But also strange from the staircase builder that he does something like that. I am just an amateur, though.

I have now taken additional photos of the support and the tiles. The tiles under the support have not changed their position, but they are hollow. The others around it have sunk, causing the joint to crack.