Sometimes the time indicator / vertical line on the workout profile falls behind during the workout. Why?
There is likely another application running that is hogging your computer's resources. Open your task manager and make sure not other applications running are taking up a lot of CPU and/or memory. Shut down those apps while running a workout. Some updater type apps and services are the most common problem-apps (e.g, Dropbox updater, Google updater, etc). You can use the task scheduler to see if these apps are starting during your peak workout times and can be adjusted.