Forerunner won't record speed/pace.

As of two days ago, my watch stopped displaying any numbers for pace or speed in any activity. It is just displayed as --:--. When my activity is synced to my app, all speed data is 0:00 and the chart is blank. I reset my watch to factory defaults yesterday and that seemed to fix it for one workout before going back to not functioning. Is there a recent software update that may have caused this? Any recommendations for troubleshooting or a permenant fix?