Node only connect to Serial Gateway if DEBUG is enabled in the gateway

[rb3rg]

Hi,
I just installed a fresh version MySensors library (2.0.?) and going through some tests here.
I have a Serial gateway with Nano+nRF24 powered with external +3.3v regulator, with enough juice.
And a node Nano+nRF24+DHT22.

Everything works fine “if” I keep the debug enabled (#define MY_DEBUG) in the gateway.
If I disable debug ( // #define MY_DEBUG) in the gateway then I get an error in the Node:

TSM:INIT
TSM:RADIO:OK
TSP:ASSIGNID:OK (ID=4)
TSM:FPAR
TSP:MSG:SEND 4-4-255-255 s=255,c=3,t=7,pt=0,l=0,sg=0,ft=0,st=bc:
TSP:MSG:READ 0-0-4 s=255,c=3,t=8,pt=1,l=1,sg=0:0
TSP:MSG:FPAR RES (ID=0, dist=0)
TSP:MSG:PAR OK (ID=0, dist=1)
TSM:FPAR:OK
TSM:ID
TSM:CHKID:OK (ID=4)
TSM:UPL
TSP:PING:SEND (dest=0)
!TSP:MSG:SEND 4-4-0-0 s=255,c=3,t=24,pt=1,l=1,sg=0,ft=0,st=fail:1
TSP:CHKUPL:FAIL (hops=255)
!TSM:UPL:FAIL

As i said before, the weird thing is that if debug enabled in the gateway, it works.
How can I start troubleshooting this issue?

Thanks.