Issues with bulk editing feature definition and feature symbology

Hi.

I have done a library of element templates, feature symbology and feature definition using the migration tools.

 Everything is working as it should, except feature definitions for meshes where it’s not able to reference to the related symbology.

When I try to manually change the reference in the feature definition and do a export, I have exactly the same as I had in the input.

 

I receive no error message when I try doing this.