Error: Dimension X should have at least one Attribute and Code

In RMS 2.0 you cannot create matrix items with gaps in the dimension array.
For example, you cannot populate dimension 1 and 3 without a placeholder entry in dimension 2.
You cannot populate dimensions 2 or 3 without preceding placeholders in the unused dimensions.

If you have created items with these types of gaps, you will need to manually fix these item entries in item properties or use the attached scripts and utility to fill in the missing gaps.

Run the scripts in the order indicated (1, 2, then 3), followed by the matrix update utility.
If you are not familiar with running SQL scripts in RMS using Store Administrator, engage a support rep by starting a conversation.
As with any script, make sure you backup your RMS database before running.

In the future make sure no gaps exist in a dimension array.
If necessary, insert placeholder entries such as a period or dash in any dimension gaps that will not be populated with actual values.
You should also not mix matrix creation between Power Op and RMS 2.0.
You should use one or the other to create matrix items, not both.

Please note that RMS 2.0 no longer supports copying dimensions to sub-descriptions.
DRS Power Ops uses this method which was the default procedure for matrix items in all previous versions of RMS (1.1, 1.2. 1.3).
If you would like to retain this feature, you must use Power Ops for creating all matrix items (not the New Item Wizard in RMS).