Vendor specific coupon added by admin not working per vendor

[Sangi0]

Admin creates a coupon and assigns it to a vendor. But when some customer buys product from some other vendor and uses that coupon code they get discount for the purchase according to that coupon.

The flow should be like if admin assigns a coupon to a vendor then that coupon discount should only be valid on that assigned vendor's products not to other vendor's product as well.