Why do I keep losing my ‘text substitutions?’
After removing the folder com.apple.InputMethodKit.TextReplacementService from the depths of the ~/Library heirarchy and restarting the computers my current list of Text Replacement shortcuts is available on two Macs that previously refused to synchronize. Both of these Macs legitimately run Sierra, but didn’t start life that way. The folder com.apple.InputMethodKit.TextReplacementService is buried somewhere inside ~/Library. Sorry, I didn’t make note of the full path — I found it using a Finder Search.
Update: A friend in the Ars Technica: Macintoshian Achaia forum reports that the path is ~/Library/Group Containers/com.apple.InputMethodKit.TextReplacementService

ᔥ A VooDoo fix for Macintosh Text Replacement Sync - Jeff Berg - Mini'app'les