BTW...the videos are quite informative, and they have manuals online AND a 215 pg pdf version for download...what more does one want?

"..what more does one want?"
 
For it to function.
 
But I think you mean why do I evaluate it as not so good, even if it would operate.
 
It is personal taste. I have watched the videos and read the on-line help for more time than I want to admit. I just don't bond with it. It seems too complicated. V-vocal or Auto-tune can be learned in a few minutes, and these get the same job done more or less.
 
Also the minimum buffer size dis-qualifies it in my opinion.
 
But I know it is immensely popular, and I am some kind of mis-fit.
 
Hope it works out great for you.

OK
 
I got another clue.
 
I went to the licence panel and "Deactivated" Melodyne because I am changing computers.
 
After the deactivation everything was greyed out. The software ran in "view only mode". This was the exact condition I was facing, only the licence was active.
 
Evidently sometimes it runs in view only mode even when the licence is good.

I don't know if this will help, but my installation included TWO versions of Melodyne...I don't recall which (not at my PC) but I do belive the 32-bit version gave me the same issues you encountered (and then some) but the 64-bit or VST3 version worked as advertised...and frankly, I can't believe how wonderful this plugin is...everything I used up to Melodyne wanted to give the simplest tuning that T-Payne sound...Melodyne lets you "preserve" the vocalists characteristics...very NICE!

I have experienced all three issues mentioned in this thread with Melodyne Editor v2 as a Region FX in X3 64-bit:
 
1. The license pop-up that lists my serial number and has buttons to activate, deactivate, etc.  I always close it except once when I de-activated then re-activated by inputting my serial number, hoping that would prevent the license window from opening.  It didn't help.
 
2. The pop-up window that says my buffer is too small and should be set to 1024.  I did change it to 1024 in Preferences/Sync and Caching/File System, but still get the warning. Maybe I need to change the buffer size somewhere else in preferences?
 
3.  Often when the Melodyne Editor editing window opens, the blobs are grayed-out and the edit tools are not available for use.  Clicking on the Melodyne "Help" drop-down menu and choosing "About" shows the plug-in is 64-bit VST3 in "Play-Back mode 2.1.1".  Something seems to be causing it to open in Playback mode, thus explaining the inability to edit the blobs.
 
These issues are intermittent and I have not found a pattern.  They happen often enough that I have gone back to using V-Vocal as a Region FX instead of Melodyne Editor.