Bluetooth paring issue

The newly delivered Arylic S50 Pro + after one day of use shows a problem with pairing bluetooth with the Xiaomi MiBox S.
At the beginning there were no problems, they paired well. After one day of use, a disconnect occurred. now the devices cannot see each other anymore … no pairing possible. I did a factory reset on both devices, but it didn’t help. what could be the reason?

Arylic firmware: 4.6.337862.30

  1. After launching Arylic S50Pro+ for the first time, it connected with Xiaomi MiBox S without any problems.
  2. Connection was kept smoothly throughout the day and night. I could freely switch the sources between Wifi / BT, connection with the MiBox S was maintained all the time.
  3. The next day after changing the source to BT, there was no connection with Arylic S50Pro +. The Mibox S initially showed Arylic S50Pro+, but it was not possible to pair. After a few attempts, Arylic S50Pro + was no longer visible at all. This is the state up to this point.
  4. I reset Arylic and MiBox to factory settings. However, it did not help.

Both devices connect to others via BT, but with each other they are unable to connect further.

Video with issue: BT paring issue - YouTube