How can I get value after merge items?

[BIM Architects]

Hi there

I have created a one schedule for Gross and For Rent area, where each area is added as a property with a certain classification. Each column has different proerties with own classification and the dash means that this property is not present in this field.

Why is this happening when I select "Merge Items" then after merging there is no value but a dash? However, the total area is OK.
How can I get value with different property (area as property with own classification) after merge items?

Please take a look a screens

Schedule with Unselected "Merge items"

Schedule with selected "Merge items"

[Christophe Fortineau]

Hello @BIM Architects,

Did you check classification of these elements ?

[BIM Architects]

Actually, these areas in the schedule are added as properties with a different classification (each column its different properties with own classification) and this dash means that this classification is not present in the given column of the schedule. Probably I have to add this information in topic to clarify.

[BIM Architects]

@Christophe Fortineau But this is the problem that I want to merge the field in the column where I have a certain classification and where it is not.