I have not noticed until recently that on some older projects when you click on Staff View, the window opens bit the scroll bar is not appearing!!! When you move the cursor across the staff area, just the arrows from the bar sporadically blink until the cursor is stopped!!! Then the arrows disappear!!!
You have to close then reopen Staff View and the scroll bar is back!
Also, while the scroll bar is gone, I can no longer grab any note and drag it. They will not budge!!!! I have to right click the note and use the editor to move the note.
When I close the Staff View and reopen, everything is as it should be!!!!!!!!
PLEASE!!!! Someone tell me I'm not crazy!!!!
BTW, my Split Notes To Tracks problem seems to have disappeared since the last couple of updates!! Thank you,
PLEASE, respond as soon as you find time. As you all know, I am quite familiar with the Staff View problem but have never had this bad of a workflow issue. Look into this, please!!!

Oh Sidroe, Sidroe, Sidroe! I hope this is not to be another record thread on the staff view.  

Don't worry!!!! I had no idea the last time I wrote about Staff problems that it would turn into a record breaking slug fest.
I am not trolling. I just want to know if someone out there is experiencing the same behavior and if it is something in settings that is amiss.

Not seeing this on CbB 2018.05.

The bug seems to be in the Piano Roll editor as well!!!!! When I click to view the Drum Pane, the Sroll Bar to move back and forth is not there until I close and reopen the Piano Roll!!!! What's the deal!!!!!!!!!!!!

I don't get this issue with horizontal scroll bars, but I do with vertical scroll bars (e.g. patch browser on SI Bass). Resizing the patch browser window by 1 pixel brings the scrollbar back.
 
Seeing as this issue doesn't manifest itself in Windows 7, I guess it must be a Windows 10 thing.
 
There's a setting within Windows 10 that might help within Settings->Ease of Use->Display:
 

 
Note that this didn't fix it for me with SI Bass (but my resize workaround still works fine), but it might help with your Staff View.
 
 

My settings page doesn't look like that in Windows 10 Home. I'll keep looking. THANKS

Search for scroll in the find a setting entry. I found the scroll bar setting in Win10 Home 1803 17134.48

Tried the search. Came back with 2 results. How far to scroll the mouse in Windows and activate sounds for mouse activity. Nothing for scaling the size of the Piano Roll.

Windows settings are more for windows and apps that use windows mechanisms. I doubt this one will affect Sonar or any other DAW as they usually have their own scroll bars built into the GUI. It sounds more like a graphics issue. Sonar has always been a little buggy that way for me. Sonar/Multidock doesn't always respond to graphical redraws properly. Sometimes clicking on the view button in the top right corner to unmaximize and then re maximize Sonar will force it to redraw.
 
On the other hand, there may be nothing to scroll if the window is currently lacking content.