Hi, I know there was a known issue with Sonar not displaying VST3 64 programs.   From what I can gather, this was fixed and is now an old issue.  Yet, I have just reconfigured TH3 Cakewalk version as a synth and while it appears in the plug in manager folder for VST3 Instruments, it will not show up in the Sonar drop down list?  I am trying to link a midi foot controller to TH3 and from what I understand, it will not receive midi messages unless configured as a synth.
Does anyone have recent experience with setting up TH3 in this way, or any VST3 programs?  Any help would be greatly appreciated, I've pumped so many hours into this and I'm losing heart.
 
Dell lap top, Sonar Professional 2016.11, Line 6 midi foot controller

The is no need to configure TH3 or any FX plug-in as a synth. Instead use the VST2/3 drop down in the standard header above the plug-in UI to "Enable MIDI Input." This will allow the plug-in to accept MIDI data from a MIDI track and has the side-effect of adding the plug-in to the synth rack. The plug-in will be listed in the FX list. This has been the way to use FX plug-ins capable of sending and receiving MIDI data since X3.