Since some recent time, my Tetra has some strange behavior: sending it midi notes in program mode every fifth note is lost and is not reproduced. There's no sound nor a voice light turning on. For every missed note, the sequence of next four notes is received ok and then the problem repeats again and again.
The same issue happens using midi via both MIDI In and USB. I've been using the 1.5 firmware before. Upgrading to the newest one (1.6.19) did not help.