scookRe-install SONAR Professional
scookInteresting, it is bundled in the SONAR Platinum core. I tested it by removing the Boost11 folder and reinstalled before posting. Boost11 is part of the Engineering Suite but I did not think it was in that installer. You could try re-installing that package. Otherwise run an advanced install of X3 and select the plug-in from the custom pick list.
scookScan settings are in Preferences > File > VST Settings
scook There are reasons for not deleting previous versions but the current version of SONAR does not depend on X3 for either Boost11 or VST scanning. It is always advisable to remove old versions before installing new versions though. If I wanted to have only the current version of SONAR installed and experienced the issues you are having, I would perform a clean install of the current version using these instructions https://www.cakewalk.com/...n-Install-Instructions