Hi @Fabio88,
From the snapshot you have posted, it seems you are a selecting the âfaceâ of an already created âmeshâ and adding it ( via the âadd selection from viewerâ) to a mesh operation. The problem is, you Can Not assign a mesh face to a mesh operation !
You must first delete the current mesh by clicking on âMesh Operationsâ for this mesh and selecting âdelete resultâ from the settings panel (see below).
To Delete a Mesh only:
.
Then you will see the âgeometryâ only (you may have to re-click on the mesh operation to refresh the viewer). Then âclearâ the current assignments if any and then the geometry face can be added by clicking it and click âAdd selection from viewerâ , then save.
I have tested this on a sample mesh of same kind and it should work.
Let me know if this solves the selection problem.
Best,
Ali.