I have the same issue, Mi-9, MIUI 11.0.5 Stable (QFAEUXM), Andoid 10, since the resent upgade the HotSpot data sharing feature does not work. Though previously i had my phone connected to my car system without any problems since the last upgrade my HotSpot is not regognized (found) even if i turn it as free (without any protection). I already tried to clear cache and reset all wifi, blutooth and Data settings but in no result so ever. I can connect my Samsung phone without any problem to the same of course car console.