The BLU H&T Display receives its time information through a compatible Shelly gateway. To synchronize the clock correctly, the gateway must be a Gen3 or newer Shelly device running firmware 2.0.0 or newer.
Please also make sure the BLU H&T Display itself is updated to the latest available firmware.
Why this happens
Older gateways, or gateways running older firmware, may not send the required BLU time synchronization data. In that case, the display may remain on UTC time, or the clock update may fail.
What to do
First, update the Shelly gateway to firmware 2.0.0 or newer. Then update the BLU H&T Display to the latest available firmware.
After both devices are updated, place the BLU H&T Display close to the gateway and run the clock update again from the display.
This should allow the display to receive the correct local time information from the gateway.