Custom Attributes in Term Templates

We are running into what appears to be an issue with custom attributes in Purview.  Once they have been saved and the template updated it doesn't appear to be possible to modify the selections that have been added for a multiple choice field type.  We are able to add new choices but not able to delete existing choices or modify the text in them.

Is this a limitation of the software or an access level issue? 

I've attached a screen shot of what it looks like normally.  Description is greyed out as well because I expired the attribute.