In case Attributes were first renamed and the Attribute Category containing them was exported to XML before importing again, the renamed Attributes may disappear.
This issue can be avoided by first making sure that the Attribute Category on the source system is re-saved.
To resolve the issue: Re-save the Attribute Category on the source system in case any Attributes were renamed, to ensure the grid layout has updated.
Even if the grid layout looks correct, re-save it, to make sure that the Attribute Category uses the latest Attribute names.
The same issue exists for Task Specifications and the import/export of Task Types.
When renaming a Task Specification or an Attribute which is also a Task Specification and you want to export/import the Task type to another system, go to the Task type Specification page first and re-save the Specification layout. This will update the layout with the updated Specification names.