Weldment Cut List - Custom Properties

I'm trying to learn weldments, because we really need to start using them here, and I've hit a snag.

I've run thru the tutorial, and the only problem I have is adding custom properties (as the tutorial teaches). This is straight from the tutorial:

In the FeatureManager design tree, right-click Cut-List-Item1(8) and select Properties.

In the dialog box:

Click in Property Name and select PARTNUMBER.

Type SUB5551 for Value / Text Expression, then press Enter.

SUB5551 appears for Evaluated Value.

Add another custom property:

Click in Property Name and select DESCRIPTION.

Type Back Frame for Value / Text Expression, then press Enter.

Click OK.

In the FeatureManager design tree, right-click Cut-List-Item5(4) and select Properties.

Add the following custom properties, then click OK:

Name
Value

PARTNUMBER
G9876

DESCRIPTION
Gusset


But when I click in Property Name, nothing happens.
Or, if I click in a box in the column under Property Name, PARTNUMBER is not an option.

What am I doing wrong??
SolidworksWeldments