IT WORKS!
What I did:
1. cut the connections of Tx and Rx
2. went back to original firmware
3. tested midi via Tx and Rx (serial) > worked
4. reinstalled moco firmware
5. reinstalled miniAtmegatron firmware
6. tested it with Tracktion 6 > it works!
Maybe the solution was to not connect the UNO with the miniAtmegatron board thru Tx and RX.
What I did:
1. cut the connections of Tx and Rx
2. went back to original firmware
3. tested midi via Tx and Rx (serial) > worked
4. reinstalled moco firmware
5. reinstalled miniAtmegatron firmware
6. tested it with Tracktion 6 > it works!
Maybe the solution was to not connect the UNO with the miniAtmegatron board thru Tx and RX.