Voices 2 & 4 are detuned

There is a known bug in the Tetra 1.3 OS which causes voices 2 & 4 to detune from voices 1 & 3 if Multi mode is ON. The work-around is to turn Multi OFF, then back ON, and voice 2 &4 will stay in tune for the duration of time the Tetra is on. This bug is fixed in all Main OS versions above 1.3