I live on the west coast and often when I manually enter a run into Garmin Connect after 9 PM, the prepopulated date is showing for the following day. It's almost as if the date is based on Eastern time, while my clock is set for Pacific time.
Also in the new Modern view, it would be nice if in Goals tab, % Complete there was a line showing where your point in time (i.e., year-to-date) target is. The graph shows what you have completed but nothing to show whether you are behind or ahead of schedule. You have this in the Classic view but not in the Modern view.