Hi,
When you are in the vendor page, the context is the vendor. So you can have a filter (using the synchronization) on the vendor.
When you are in the product page, the context is the product, no the vendor. So you can't display the module in the same context and have the same result.
Regards,
Jerome - Obsidev.com
HikaMarket & HikaSerial developer / HikaShop core dev team.
Also helping the HikaShop support team when having some time or couldn't sleep.
By the way, do not send me private message, use the "contact us" form instead.