Never done casting let alone worked with Chinese factory to ship hundreds of units but: this sounds potentially intentional at factory's end. It's plausible that these fins didn't pass factory guy's manufacturability gut DRC who would made changes thinking the customer would just give in. IIUC molding people in general don't like corners and narrow channels with no sprues and/or gas escapes. Especially the outer ring of pins appear to be exactly where they like to place sprues.
I wonder how this problem was eventually solved. The final product seem to retain the number, height, draft angles of the fins, but fillet radii appear to have increased(2mm -> 5mm?) and the entire body shows more material shrinkage at the outer edge of the body as well. Was it just no pins and higher defect rate, or something else entirely?