I restored the tasks that were deleted from C: \Windows\System32\Tasks (see other solutions above) and the Task Scheduler recognized them.
The original cause(s) of the ACL corruption is still out there and could strike again.
I may have iniated the problem by performing Defrags in Command Prompt (eg DEFRAG C: or DEFRAG C: /B) or MS could have caused it through a downloaded update.
There is no need to enable this option if your device is a standard USB device that when plugged in appears as a drive letter from Windows Explorer.
Music Bee will allow you to select any folder and treat it as a device for syncing (you may need to configure a Music subfolder as well).
(This means that a track on more than one playlist will be synced more than once.) The file names are based on the playlist order.
) The path prefix applied to files listed in a playlist, where \ means the path is relative to the root folder of the device.
You must have replay gain tags in the file for this to work.
) This setting overrides the media storage settings and forces each playlist to sync to its own folder.
To use an MTP device (which includes most Android and Windows phones), you must first check "detect MTP devices" at the top of Device Preferences.