What MIDI-to-USB interface did you purchase? Did this device come with manufacturer-specific USB device driver software?
Did you try all the available direct USB ports on your computer?
Some "generic" MIDI-USB cables that are supposedly class complain/plug-and-play devices may not provide a stable enough communication line between your computer to the Floorpod, but there's always a chance that an issue might be occurring within the Floorpod unit (MIDI-related hardware functions).
If you have another MIDI hardware unit capable of receiving and sending MIDI Program Change data, you could troubleshoot whether the Floorpod is receiving and sending MIDI program change data. This requires another unit acting as either the sending device or receiving device for MIDI Program Change (synchronization) control.