I worked with URC on a bug I found with the Samsung IP driver for Total Control.  When entering the MAC address into the Total Control software it wasn't always accepted correctly which caused issues with the power on (WOL).

I found that on larger jobs where I had more than 2-3 TVs I was copying and pasting the MAC address from a spreadsheet which created a carriage return at the end of the MAC address.  This was a hidden, but wasn't parsed correctly so the MAC address was corrupt.

URC fixed this in an update and now the MAC has to be formatted correctly to be accepted.

I know you are using Savant, but maybe something similar is happening?