Debugging in Xcode: "Wait for next launch/push notification" not working.

Question

Okay: I'm stuck!

I wrote a little command-line-tool which I successfully debugged using the "Wait for next launch/push notification"-option, the other day -- worked like a charm.

I updated Xcode.

Now, I wanted to investigate an edge-case of said tool and therefore wrote a very short test-tool. I...

1. set the exact same option,
2. added breakpoints hit "Build and Debug",
3. sheet pops up, (now a new look with two additional buttons...well, whatever)
4. switched to Terminal, started the app and
5. ...nothing happened; my breakpoints don't get triggered!

Is there anything I am missing or is this a bug?
I tried running the executable with and without clicking the new sheet's "Ok"-button. Either way Xcode's GDB-console tells me

Waiting for process 'CLIEncoding' to launch.
Attaching to process WHATEVER_THE_PID.

The tool runs and finishes without ever hitting any of the breakpoints.

Ideas anyone? 'Cause I just recently ran out of mine...

update:
I just checked back with my other project: delayed debugging still works like a charm there on this very machine.

I am now completely puzzled!

Settings in the "Executables"-inspector are equal, only difference being the older project is the command-line-helper of a Cocoa-application that started out on 10.5, while the newer project was created as a "Command Line Tool" in my current Xcode.
end update

For the record, "System Profiler"'s info on my dev-tools:

Developer Information:

  Version:  3.2 (10M2262)
  Location: /Developer
  Applications:
  Xcode:    3.2.3 (1688)
  Interface Builder:    3.2.3 (788)
  Instruments:  2.7 (2529)
  Dashcode: 3.0.1 (330)
  SDKs:
  Mac OS X:
  10.5: (9L31a)
  10.6: (10M2262)
  iPhone OS:
  3.2:  (7B367)
  4.0:  (8A293)
  iPhone Simulator:
  3.2:  (7W367a)
  4.0:  (8A293)