Yep, you and I want to rename for different reasons, but ultimately we've found that the renaming capabilities aren't behaving consistently so I had also directed tech support to this thread. I'll follow up when I hear more.

When you say immediately, what do you mean exactly? For instance, I rename the following way - what step does it rename after?

1 - Open Plug-in Manager
2 - Select VST in left pane
3 - Double click a VST name in middle pane
4 - Type a new name in text box that opens
5 - Click OK
6 - PIM reverts to state as at step 2 with plug-in renamed in middle pane

I'm assuming after step 6, no change has ocurred?

KPerry
When you say immediately, what do you mean exactly? For instance, I rename the following way - what step does it rename after?

1 - Open Plug-in Manager
2 - Select VST in left pane
3 - Double click a VST name in middle pane   ( I select a VST effect )
4 - Type a new name in text box that opens
5 - Click OK
6 - PIM reverts to state as at step 2 with plug-in renamed in middle pane ( I close the Plug-in Manager and Open my list of effects to add to my project and the VST effect has reverted back to the original name ).

I'm assuming after step 6, no change has ocurred?

 
See my ( edits ) above.

I'm confused - are you saying that when you select a VST effect in (3), a text rename box appears?  The box with a title of "Friendly Name", that is.
 
Also, if you run the PIM from within SONAR, you will indeed not get the FX renaming (I've just confirmed).  Run it from outside.
 
I consider plug-in management such an "admin" function that I'd never run it from inside SONAR, but do all plug-in management after installing/deleting/updating a plug-in (including renaming it).  SONAR is then for music :-)

Ok this might be simpler. 
 
Open the plugin manager.
Select a VST Audio Effects (VST) in the middle pane.
Click on Plugin-Properties below the middle pane.
Change the name in the upper dialog box.
Click ok.
What is the name of the VST Audio Effect (in the middle pane) that you just changed?
 
For me - its the original name.  It does not save
 
This is scenario #1. 

NOW.... Do what I did above - and then.
 
Now go into plugin manager and select that SAME plugin. 
 
Click on properties and then look at details....WOW... there is the name that I typed.  
 
Its saved in Details but not saved as the name.

KPerry
When you say immediately, what do you mean exactly? For instance, I rename the following way - what step does it rename after?

1 - Open Plug-in Manager
2 - Select VST in left pane
3 - Double click a VST name in middle pane
4 - Type a new name in text box that opens
5 - Click OK
6 - PIM reverts to state as at step 2 with plug-in renamed in middle pane

I'm assuming after step 6, no change has ocurred?

 
Correct - the list reloads after a rename, but scroll down to the VST, and it is NOT renamed 

I give up then - I've just tried this inside and outside SONAR and it works as expected.  All I can think of is it's a permissions issue somewhere in the registry.

KPerry
I give up then - I've just tried this inside and outside SONAR and it works as expected.  All I can think of is it's a permissions issue somewhere in the registry.

I don't know how to post pictures, but here is a link to 3 pictures concerning what I'm doing. 
 
Pic 1. I open up my Pluggin menu.
         Select VST3 effects Audio Effects (VST3) (in my left pane)
         Randomly select a waves plugin (in my middle pane) - LowAir Stereo
         I click the Plug-In Properties button below the middle pane
Pic 2. I change the name of the pluggin to Waves LowAir Stereo as shown
         I click the OK button on the bottom
         A spinning circle appears ( At this point the name in the middle box should have changed. )
Pic 3. LoAir Stereo still shows in the middle pane  WHY?
         Waves LoAir Stereo properly displays in the Plug-In Property box?

http://gtgsolar.com/PhotoAlbumsPro/Album_nn3rx9/#/0