MT5 stores 1 minute chart candles, and creates the daily/4 hourly/hourly/other candles from those 1-minute candles in the client terminal when the user changes the time-frame.
Fusion had not been founded until several years ago, so the chart history at the time is imported history. To ensure the live server is running efficiently, we do not store the 1-minute candle data on all symbols back to very early dates from before Fusion started. On the demo server, we are able to store additional data as performance is less critical.
Example given:
With this issue, those daily candles are formed because only daily candle history is available from before a certain date, and MT5 is trying to convert that daily candle data into a 4-hour candle in the earlier dates.