Choose, for each size chart, which Business Central article attribute holds the size value.
Each row connects:
a Centra Attribute – the list shows the size charts in your Centra, and
a Business Central article attribute that holds the size.
Good to know
Use an attribute that holds the size name, not its ID.
If the list is empty, check that Centra is connected. An empty list almost always means the connection, not the setting.