You're actually right!
It is an development build. So there's no debug symbols, but no optimisation either.You can still trigger breakpoints and read log messages, but can't see which function triggered the log message / Breakpoint.
Not a debug build. Not a development build, either, despite what the .ini might suggest. It's a shipping build. Mordhau runs on a custom build of Unreal Engine that contains some minor changes, which also include certain debug message functionality that is harmless to performance but is useful to have.