Hi @Barakaz ,
I am not sure, but could it be that you have used a Cube with a Subdivision Surface Modifier Applied, and then, in Sculpt Mode tried to use the Mesh Filter, set to Smooth?
This is difficult to explain, but it is already smoothed as much as it can be with that amount of geometry, so it will just shrink the Mesh…
It’s like this: how can you ‘smooth’ a Cube with 8 Vertices? If you first Subdivide it (Simple) once, so it still is a Cube, but has 26 Vertices, ‘smoothing’ it will turn it into a more spherical Object…
Try Remeshing it first and then the Smooth Mesh Filter should behave more like you’d expect.