I received this reply from another forum:
Hi wildoat,
Yes, the anniversary update for Windows 10 has made some significant changes in default settings that will have a rippling effect to other functions that depend upon these default settings. The Send To context menu and extended context menu is one such folder that depends upon default settings. Also, the upgrade could have changed some of your settings. I'll try to help you recover send to items you lost, but currently the new items are beyond the user's control. To make sure that others that read this understand, I'll explain some basics that you seem to already understand.
When you right click an item the menu that shows is called the context menu.
When you hold the Shift key while right clicking an item the menu that shows is called the extended context menu.
The biggest difference between the two is in the Send To menu. Usually, the extended context Send To menu will display more options than the regular context Send To menu. The added send to items are the default locations for Windows created folders.
The anniversary update for Windows 10 changed the settings for many of these folders (and some application such as the App store) to move them from the background to "in your face". This is what moved some of the Send To items from the extended context Send To menu to the context Send To menu. The extend function (holding the Shift key while clicking an item) works from the attribute settings of the item. The update changed those settings and thus some of those default items will not display in the extended view. Thus, less in the extended than in the regular because some items have been moved from the extended to the regular by attribute changes. These same attribute setting changes may have changed the attributes of some of the send to items that you had.
So let's see what you have and how to fix any lost items.
To see just what is in the Send To folder that displays with the context menu you need to open the Send To folder:
While holding the Windows key down press the R key.
This will open the Run box.
Delete anything already in the Run box and type in shell:sendto and press the Enter key.
This will open the Send To folder in Explorer
Windows Explorer must be set to show hidden and system files to make sure you can see all the contents of that folder.
In another Explorer window right click a file to display the context menu and match the items in the context Send To menu with the contents of the Send To folder. The items displayed in the context Send To menu that are not in the Send To folder are default settings by Windows. Windows will also add all detected drives to the list. If an item is in the Send To folder doesn't display in the context Send To menu, then this usually happens because the attributes for that item in the Send To folders have been changed to Hidden. Unchecking the Hidden attribute will allow that item to display in the context Send To menu.
There are many that are unhappy about the changes with this forced update. I suspect that soon there will be work arounds and hacks to undo some of those changes....I've been working on a few myself. Keep an eye open and let us know if you find one. Users don't mind updates to protect their system, but updates to make you use their products to increase their sales is like your ISP spamming you the customer.