I had symptoms below and I researched and took these actions - the 'problem connecting - xxx' message appears to have been fixed. I have not done the "last option" below...not sure what that will do!
2/3/21: After Android 11 - re-paired both phones (ensure that you are allowing access to Messages - watch out for separate prompt) - but while watching phone, getting 'problem connecting - turn device off and back on' Bluetooth message on the phone ?? Rebooted phone, no help. On phone: Settings/Connection Pref/turned BT off/on . Tried deleting BT cache and storage….try again. Then try this more thorough 'cleaning':
• Cleanup phone: Turn BT off on phone; delete BT cache and storage on phone; Settings / System / Advanced / Reset / Reset Wifi…Bluetooth.
• Then reconnect phone to home Wifi. Leave BT off for now.
• In car, choose the correct driver profile for phone you're going to connect.
• Move car away from home wifi so it's not connected to home wifi. Use Device Connections in car to remove all phone connections entries (press hold Delete button, then mark and Delete).
• Then shut off car for a minute / open door to ensure they are deleted.
Turn BT on on phone.
• Change name of phone in the BT section! ("Mi A3 Doug", etc.) Re-pair one phone at a time as normal and ensure you allow access to messages via separate prompt - on phone. On the car it should show the phone headset and music icons for the phone. Wait for the "contacts downloaded" message.
• On phone, change "Kia Motors" BT name to "Kia Seltos".
• Can turn car off / open door; car back on an ensure car connects with correctly named phone. Examine the BT screen on the phone for the car connection - should stay just plain "Active"! (no "problem connecting….").
• Test with voice command "Send Message to…", "Call xxx", and try playing BT music.
Last option would be to reset the head unit - press the tiny button for a couple seconds….