In desperate need of a fix for this!!
Don’t know if anyone out there can shed any light on this problem
I can select several tracks and most others on the forums seem to also be able to - so no problem, unless you can provide some useful information… 
For example. Describe the steps you are taking to try and select multiple tracks and at what point does this stop working?
Step 1. Add more than one audio track
Step 2. Try to highlight / select more than one
Step 3. realize that only one track can be selected at a time
On my Win 10 system I can highlight as many tracks (or even separate events) as I want if I hold the “shift” key while selecting them.
Regards 
Yes.
This is the kind of problem that only if anyone else had ever experienced it and knew what was the cause of such behavior could they help me. If you haven’t experienced it then it doesn’t apply to you. And since no one has yet come forward and said they have experienced this issue is still important information for me. It indicates the problem is within my specific setup somewhere.
I dont use mac.
But I have seen users having similar issues with other mac systems. Not only program spesific, but global on the system.
Is this major annoyance only happening in Cubase?
Is it happening if you run your OS in safe mode?
Might give some lead information, on where to look. Troubleshooting the issue.
So you are saying shift-click and alt-click (or hatever it’s called on a mac) doesn’t work? If so, is it isolated to cubase or also not working in finder and such?
That is what I’m saying. None of the modifiers worked to select multiple tracks, the highlight kept jumping to one. It’s only in Cubase.
Miraculously the problem went away today, but it might be back. Certainly strange behavior.
Though intermittent, I have experienced the “shift-select” not working you described. Holding Ctrl also does not work when this phenom is happening using Windows 10 and my Cubase. What I do to fix it is close the Cubase project and then re-open it. The I can shift-click a stack of tracks as expected. HTH
Sorry for the delay in my reply. Though I have Cubase 10.5, I mostly use 8.5 because I need to use certain 32 bit plug-ins. Once again I experienced the intermittent problem where I can’t shift click a stack of tracks in the project window (or a row of channels in the mixer) in Cubase 8.5 a couple days ago. So I Googled it and found this thread on the Cubase forum to see if there was a better work around besides closing and re-opening the project. The lack of shift-click select also happened a couple months ago (in Cubase 8.5 on Win 10) so thankfully it’s not too much of a hassle (knock on wood : - )