I'm having issues too: The workflows don't appear to be broken, the just never get called: it seems like the websearch always gets the precedence over a recognized workflow: e.g.
radd some reminder
should call the reminder-workflow: it also shows up in the quick-list up to the rad - but when it is completed, it gets replaced by the websearch and hitting return then searches for radd some reminder in google. I upgraded to Sierra on the week, had no issues previously with any of the workflows.
PS: Adding a comment/log-entry to a workflow confirms, that the workflow is never called and the entries get intercepted by the websearch.