I still haven't heard back from Ken, but I did find that the sound alerts you had configured in BI4 do not populate the registry UNTIL you update the sound file path and then save it. Once you do this, it will ad many more keys in the Computer\HKEY_LOCAL_MACHINE\SOFTWARE\Perspective Software\
Blue Iris\server\users\xxxxxx\OnLogin\0 folder. This along with something new in 5.0.1.0 that keeps sounds from going through a RDT connection. To fix mine I just deleted my on connect alerts for my 3 users, which wasn't so bad.