Keni I don't think you've ever offended anyone, at least not on this forum.
 
Happily this is a problem that I don't see. I ditched a load of old vsti's several years ago when I went fully 64 bit.
 
This could be something as simple as the wrong type of variable defined to populate the list.
 
I know in Visual Basic there is a specific data type known as BYTE which has a range of 0 to 255

e.Blue
99% of the time whenever I want to add a new VSTI instrument to SONAR I do the following:

1. Click on the Synth tab in the 'Media Browser'
2. Click the little '+' sign in the upper left corner
3. Go to 'Insert Synth' and browse to the desired VSTI instrument from my custom menus.

 
Since the latest update, the 'Insert Synth' option can now become permanently grayed out and can no longer be selected.

 
I had actually encountered this same bug in past SONAR versions and discovered that it seemed to be related to the number of VSTIs that were in my Custom Menus. At somewhere around 255 VSTI plugins the 'Insert Synth' menu option would become ghosted out. Previously the only workaround was to reduce the number of plugins in my custom menus until the 'Insert Synth' option reappeared.
 
Since the latest update I have discovered that selecting any of the new 'Sort By...' options immediately causes the popup menu to become grayed out. Since there is no custom menu involved this time, the selection is not only permanently grayed out but you can no longer switch back to any of your custom menus via the Plug-in Layouts option. The only workaround that I have found is to go to your plugins folders and physically reduce the number of VSTI plugins in that folder until it gets below 255 vsti plugins. I did this by using .ZIP to temporarily compress some folders since SONAR can't scan zipped folders. Once you are below 255 VSTIs again, you can them switch back to one of your custom menus. 
 
Keep in mind that I am only referring to VST Instruments. So far I haven't encountered any similar issues with VST effects and also remember that effects can't be inserted using this popup option.
 
BTW, the new Categories customization features are seriously slick. I can't wait until this bug is fixed so that I can actually take advantage of them.
 
Regards,
-e.B

We'll look into it - do you have an official CWBRN case number? It shouldn't be graying out that item since there are no plugin limits now - we should just be popping a menu with all the items. Some corner case must be doing that.

I cut mine down to 7, though I may reinstall Rapture Pro

Kamikaze
I cut mine down to 7, though I may reinstall Rapture Pro

That's more my style...a few instruments I know well.
 
I'd definitely recommend reinstalling Rapture Pro, the original bugs have been cleaned up a lot and I hear another update is forthcoming (although I don't know when). I'm working on some more expansion packs for it.

The CWBRN with my registry settings dumped and attached (which can be used to simulate having enough plugins to make the synth button grey even if you don't have those plugins) is CWBRN-52803 though it was submitted so long ago I'm not sure the registry dump is still valid.  This latest release still has the same problem(s).  It's not quite as simple as 255 entries though, the actual count and when/how the synth rack grays has a number of factors.  I'm sure there is slightly more to it.  I would love to see someone look into this.  I'd also be happy to re-dump my registry if that would help.  Or make my workstation available via some remote sharing if that would help.