It does not exist in mac os as it does in Windows I think but..

There most be some setting though in mac os, were you can choose to install it anyway.

Maybe this helps? ... s-on-a-Mac
I might have seen it there in my synth1 presets, I will search for it :)
I am working on the drums, but right now am also a bit fed up with the track.

No big deal I will finish this, but right now a bit out of motivation. This often happens to me when covering stuff.

Its 90% done
You could cut frequencies, and or just lower some frequencies of certain instruments.

If you do it too much its gonna sound weird, but it can help.

He does it somewhat different then me, but you will get the idea. He cuts(lowers) certain frequencies
Do all notes have the same velocity in the piano roll ?
I am just starting to serious pan some instruments myself in my tracks.

I have noticed it does help, to not have one big mess of sound.
If the reply of musikbear did not fix it:

Were did you install LMMS from ?

I am openSUSE tumbleweed, nice to see another openSUSE user.
Do you already pan the other instruments ?
Thank you :)
That is weird, did you first connect the midi keyboard , and then start LMMS ?

What version of LMMS are you using ?