Thank you for providing this great bulk data.
I found only 214,168 design patents out of 765,312 (27.9%) have corresponding USPC data in "g_uspc_at_issue" table in bulk data. Missing USPCs constantly are found throughout granted years.
I also found that this comes from missing primary USPCs. As you see in examples below, all of primary USPCs are missing in the "g_uspc_at_issue" table.
Here are examples. All of design patents are randomly selected.
g_uspc_at_issue: D16/300; D16/325; D16/314; D16/312
PPUBS: D16/309: D16/300: D16/325; D16/314; D16/312
PPUBS: D10/120; D10/118.2
g_uspc_at_issue: D15/135; D18/50
PPUBS: D15/122 , D15/135 ; D18/50
Thanks a lot in advance for your answers and help!