[Piglet]

I am new to this forum and BMW. I just purchased a 2017 420d SE, and it is in mint condition, but unfortunately it does not have the fancy HK stereo/audio system.
The car does not have Apple CarPlay either.
Two weeks ago, when I sync'd my Apple iPhone 7 running iOS 14.3 via Bluetooth, I could see the Spotify App appear on the screen of the Pro SatNav.
A few days ago, I upgraded the iOS of my iPhone to 14.4, and now I can no longer see my Spotify App on the screen of the on the Pro SatNav. It's gone.
When my son connects his iPhone 7 running iOS 13.x via Bluetooth, he can see his Spotify App appear on the screen of the Pro SatNav ...but the volume of the music is very low despite that fact that he definitely has the volume of his iPhone turned up all the way. We have to turn the volume of the car stereo up almost all the way just to hear the music being played at a moderate volume.
Has anyone else experienced this? Do I need to update the software of my Pro SatNav/Entertainment unit ...or perhaps of the iDrive in my car?
If I am reading the info screen correctly, it looks like the car is on version 7.5.13