I spent all day yesterday trying to debug my code because it was failing with an old error that I though I had fixed.
I would click in compile and run, which showed me the terminal with my program running and failing. Then the debugger would give me any kind of weird errors that I didn't really understand why they were happening. It turned out that the compilation of my program had failed but 1) the messages with the errors are blue/grey (instead of the bright red errors that other features use), so I didn't bother to read them because 2) the terminal opened and showed me my program being executed (but it was actually an old version of my code).
I thought it was Codeblocks being a bit ambiguous, but I've tried now build+run, and it has failed to open the terminal and everything, which I would think it's the expected behaviour when failing.