How do I get the MS variant data to export to UB and populate the COMP_VARIANTS field?

[dbur]

Some of my UB parts have a value in this field (default1), but when I set up variants in MS and export nothing seems to come through.  I don't know how the values came to be in the few parts that do have entries.

I want the UB BOM export column COMP_VARIANTS field to be populated by the settings in MS.

Thanks.