The MobiLink server has a GUI console with a scrolling window of log messages, as well as a /tmp/logs/ml.log log file. In the current default configuration, the console and log files show only warning and error messages, but you can turn up the verbosity level so that each server initiated push message is shown as well.
As you test push notifications to user devices, monitor these logs to see that the notifications are indeed getting out of UA and over to MobiLink. If the push synchronization is not working on the user’s device, have users start analyzing things down-stream from MobiLink to isolate the error.