[exim] Strange response for exim -d+all

Good morning everyone, hope you all are well.

I'm not sure what I have missed or am missing, but on a centos7 system, as
I issue that command to debug the router, it is coming back to prompt
rather than continue to listen to the socket.

Same is true if I try exim -d-all+router

To be honest, I rarely needed to use this given Exim is so brilliant on
FreeBSD. Has the expected behaviour for exim -d changed and I have failed
to notice that?

Would appreciate if someone could please confirm.

Best regards