Really? I would expect that would result with only POs in status B, and none in D.

"PurchOrd:B" || "PurchOrd:D"

will just evaluate to

"PurchOrd:B"

. When you are filtering on multiple values, you need an array, so I would expect it would need to be

['status', 'anyof', ['PurchOrd:B', 'PurchOrd:D']]