I have noticed that the download center doesn't actually always refresh, especially immediately after starting the engine.
I've had to spam the download center button in the app list to make it actually check for updates and sometimes forced it to recognise the need to refresh by cutting the internet connection from the car.
I hope you get it fixed soon and please post how you did it when you get it.
Because of this problem I had de-installed the Spotify app. I could not re-install it (new app file showing 0.00MB), until yesterday: problem solved as I have been able to install the app (and use it). Part of the update appears to be an improvement in the login procedure (verify new login on another device you have e.g. smartphone). So for me, case is closed now. Thanks Spotify & Volvo resolving this in reasobale time.
Abosey1: note that the car's announcement of "a new update" might not be for Spotify, actually it won't be, after you would have de-installed it. A new update often refers to map updates - you might want to check that out. In my case (Netherlands, XC90) Spotify duely showed up as a "new app" which I installed normally and works fine now.
I understand, but it's not the map or something else. My spotify is gone from the installed app and in "new apps" spotify doesn't show up. So for 5 days the spotify app is gone and the car says there is an update.
48 hours later, Spotify has reappeared in my list of Aps I can download. Which I did and installed ok.
There MAY be some conflict if you have a map update going on (not download, the tedious update process that goes on in the background with low priority) which might prevent Spotify app from being seen.