We use a custom property called "Lanco Part Number" to store our internal part numbers in assemblies and parts. It does not always match the file name, ie: Lanco part number "AAA-A12-34567" would be file name "1234567.sldprt" with the alpha characters and hyphens omitted. On our BOM the lanco part number is displayed and we would like to balloon assemblies using this data. When promoted assemblies are used, or when ballooning a part within an assembly that has a "lanco part number" we get blank boxes when the option to use the custom properties "lanco part number" is chosen. The item number works as expected, why cant it reference the Lanco Part Number column of the BOM correctly?