Piotr, is this a new problem? I had a similar thing happen where I would not be able to hear the metronome after change the sounds it used, & the problem came after an update. Someone on this forum suggested toggling the global FX button on your control bar, saying this was a known bug. That did the trick.
 
Occasionally I will have no metronome sounds when I go to record even if I have not changed the metronome sounds. Usually it will come back on the next take, but if it doesn't, I toggle the global FX and that seems to do it.
 
Good luck.

Thanks, Clark, for answer. In fact it is not new issue for me. I observed it earlier but it was not 'critic' so I used some workarounds (like adding additional bar to project).
 
But curiosity made me to test all  possibilities (in fact not so many only 4). I am turning on/off only 2 buttons (Metronome During Playback and Metronome During Recording) and only 1 of 4 has such mysterious issue.
 
I tested toggling FX as you suggested, no difference. Interesting as I reinstalled OS from scratch so I would rather expect solving strange issues. I will try to check this on the same machine with different OS and using different audio interface I have secondary profile for machine for less serious applications.

This is really interesting. I tested it on different profile.
 
Exact the same machine but different OS (W7Pro instead of W10) and X2 instead of Platinum (disk with my old install) and got exactly the same results. When only Metronome During playing is ON count-in cannot be heard.
What's more I connected different audio interface and changed drivers and got again the same results...
Hm, kind of side effect... ? Luckily no big deal and easy workaround exists but seams very old problem :)
 
 

Piotr, that's all very strange. I do not have deep enough knowledge of Sonar to offer any other ideas; hopefully someone here may have some other ideas.
 
Good luck!

Anderton
I didn't know you could have a count-in when the metronome is set for playing only. In my version SONAR starts immediately if you're not recording, regardless of whether you have a count-in or not.

This is key, i.e. the count-in only occurs when you hit R (record) but without sound.  Count-in doesn't occur on normal playback (hitting space bar).  I'm sure it is because Metronome During Recording is deselected.  However, it does make sense that one might want an audible metronome count-in to begin recording without wanting the metronome sound during "recording".
 
Piotr, my Sonar behaves the same way.  I have no idea if it is as intended or perhaps just an oversight.

The fix (if it were to need one) would be to add tick box option for the Recording Count-in.  As it is now, it is tied directly to the Metronome During Recording option.  But it is odd that in the below situation, the count-in obviously occurs albeit silently.
 

 

Wren, of course I pressed 'R' (not space bar) to start recording and as stated before the only change in my tests was different configuration of Metronome During Play/Recording buttons (which do the same as options in Preferences dialog you included).
 
The idea was to have metronome click during count-in before recording but not during recording itself and also to have metronome during playback. It is kind of curiosity from me I am not looking for more workarounds as there is very simple like put both 2 buttons in OFF state before recording and turn ON MDP if need before playing. But thank you for taking a look at this issue :)

No problem.  I was actually responding to Craig's post and just confirming the behavior you're experiencing.
 
All the best!