We've been investigating this. What we've found is that some MIDI devices do not respond well to what is called "Running Status" messages. Here is a really good in-depth explanation of what running status means:http://home.roadrunner.com/~jgglatt/tec ... ec/run.htm
Basically what happens is the Softstep announces a program change and sends the corresponding status byte the first time, but then for subsequent program changes it is following the running status spec and just sends the data byte. About every 11th program change it re-announces the program change status byte. This is when MIDI devices incompatible with running status messages see the program change. Nowadays most MIDI devices are compatible with running status style MIDI since it is faster and more robust. So devices that use older MIDI implementation need to see the status byte every time in order to recognize the data.
In an effort to be compatible with everything we are planning a firmware update that will send status bytes with every message. We will announce the new firmware once it is ready.