Well, I have similar issue on one of my comp. I reinstalled whole OS and Sonar but still issue persist. I tried to report it but nobody from support did care about it. Also at some version CAPS switch stopped to work (this issue repeats on both my machines).
Unfortunately I didn't find solution. I am using virtual keyboard version with alpha keyboard (shortcut Alt+0) if don't want to bother with connecting midi and need something simple.