@ebrahim, since the extension worked in 5.10, and then crashes 5.12 I think this is a Slicer regression and we should somehow make it failsafe. We don’t know who else might have depended on this older behavior.
@muratmaga FYI, the DKFZ team behind nnInteractive contacted me and @lassoan that that will be making an updated SlicerNNInteractive extension available but it’s not ready yet. This will support a new version with improved features. So things are in flux for a while.