I am still using SW2014 SP5.
When creating Reference Dimensions in assemblies, the name is auto-assigned and grayed-out.
I have a file that is a copied-and-modified version. An existing Reference Dimension has gone "wonkey".
Yes, I could just delete and recreate... However, I have linked information to it and I have a number of other similar files with the same setup. If I delete and recreate, I won't get the same name, can't edit the assigned name, will have to "special case" this one particular assembly so it is different than the others in the group. My "particular about details" nature is SCREAMING. I think they have a three-letter acronym for that...