Forerunner 965 Swim Drill Log Error

I use the Drill Log on my Forerunner 965 to record time and distance for kick sets.  I have done so successfully for years.  Last week an error started occurring.  It may have started after the latest update.  When I press the "Back" button to end the drill my watch totally restarts and displays the watch face while losing track of the drill I am doing.  This morning, I tried pressing the "Stop" button instead, and the same thing occurred.  The drill lasts approximately 10 minutes. The "Back" button works properly for all of its other functions on the watch.  If I start a drill and then immediately end it, the watch allows me to enter a distance and record a "drill".  Anybody else experiencing an issue with the Drill Log?