Can anyone shed some light on why these surfaces do not join as expected?
It must have something to do with them having singularities, yet I never ran into this type of problem and although that might be because I never had this situation in a model, yet it feels buggy they are not joining.
Select all and run _Join. It does join but not into a single polysurface.
UnableToJoin.3dm (97.7 KB)