When using 'Last Half Hour' as the timeframe (or any 'Last ...' option) it does not reflect the last X as time goes by. The screen will refresh but the display will remain at whatever timeframe from when you made the selection as an absolute value.
When switching to 'This Day' etc it shows the data for today as the timeframe is set from 00:00 to 23:59 for the day.
When using 'Last Half Hour' as the timeframe (or any 'Last ...' option) it does not reflect the last X as time goes by. The screen will refresh but the display will remain at whatever timeframe from when you made the selection as an absolute value.
When switching to 'This Day' etc it shows the data for today as the timeframe is set from 00:00 to 23:59 for the day.