CORD-2932 emit warning if driver.enabled is False

Change-Id: Iad8fbaf618aa9ce45e9865c740df33805a54c16d
diff --git a/xos/synchronizers/new_base/event_loop.py b/xos/synchronizers/new_base/event_loop.py
index fdf3671..efcd2be 100644
--- a/xos/synchronizers/new_base/event_loop.py
+++ b/xos/synchronizers/new_base/event_loop.py
@@ -430,6 +430,7 @@
         # Cleanup: Move self.driver into a synchronizer context
         # made available to every sync step.
         if not self.driver.enabled:
+            self.log.warning('Driver is not enabled. Not running sync steps.')
             return
 
         while True: