It does change depending upon from where you backfill, Data table or Vwap. Their start time for candle differ.
When I first used RTD, a friend on mine who taught me how to set up and use RTD told me we use either VWAP or Data table. Since then everytime I set up RTD after reformatting my drive, I have never bothered with any settings of VWAP but only Data Table. Even though I do everything as per your instruction videos, I just skip VWAP settings. And when I do backfill, it automatically opens Data Table and does the backfill. Am I missing something?