Probe Basic ATC Setup Problems

It might be helpful to turn on debugging in terminal to see exactly what point in the sequence its getting stuck.

INI file
[DISPLAY]
DEBUG = 0x10

And then start LCNC from the terminal.

Attempt your tool change (M6 T1 or T1 M6) and when it gets hung up, use ALT-TAB to switch to the terminal window.  You should be able to see what commands are going on in LCNC and likely a hint as to exactly what is hanging up.

I agree with spumco, run in terminal so the debug messages show the failure point. Probably something simple I had 0 where an o word should have been that chased for 2 days troubleshooting.. probably started at it 50 times and that was with debug on telling me where the problem was

Maybe post your toolchange sub also