Nord just told us about this one:
The new Nord Electro 4D OS v1.06 fixes a USB-MIDI bug that could cause the instrument to hang when receiving/transmitting USB-MIDI messages. The update also fixes a bug where the onboard keyboard could produce unwanted Note Off messages in MIDI Local Off mode. An issue where the piano engine under certain circumstances could produce a click when releasing the sustain pedal has also been resolved. See the update history for a complete account of what's new in this update.
Get the new OS update Nord Electro 4D
Seamless audio and MIDI switchover between computers