We had a similar issue with our in house automation system and a new Broadcast Tools 4.1 MLR Switcher. We had successfully used and older BT 4.1, but this one would not respond beyond the flashing light showing communication. We used PUTTY (https://www.chiark.greenend.org.uk/~sgtatham/putty/latest.html
) and referred to the manual and found there was indeed a syntax change. The old units asked for a "*04" to switch the switcher to port 4, while the newer units wanted a "*004". The purpose of the new digit was to allow several of the units to be used together. Once we figured that out, it meant either a change to the AUTO software or an external solution. We (actually engineer friend Burl!) went with arduino (https://www.arduino.cc/
) between the computer and the switcher to "convert" the *04 to *004. Worked like a charm, and will be helping us get our sister station WIVH in the Virgin Isalnds back on the air hopefully within the next week. We have been off the air since Hurricane Maria devastated the island.
Hope this helps!