MS510TXPP Only Allows 8 MAC Addresses For VLAN

I have a MS510TXPP that I'm trying to use to segregate some traffic using VLANs. I have a switch connected to it that has a mix of multiple devices that need to be on different VLANs by the time they get to the router. So I had been using the Switching > VLAN > Advanced > MAC Based VLAN Group Configuration feature. However, I was now going to add a 9th MAC address to the list and I ended up getting the error: "Number of ranges exceeds the maximum (8)." Is there a good reason for there being such a low limit on the number of MAC addresses that can be VLAN tagged? Is there a setting that I'm missing or some other reason that 8 makes sense?