Already tried this on the Apple forums and no response, so I figured I'd see if any gerbils could help me out...
I have an iPod Touch 128GB - recently when I updated to the most recent OS it stopped working correctly in both of my cars.
I have a Dodge Challenger (2019) - it'll still play music but can only be controlled via the iPod itself; you can browse using the cars screen but it has no effect - it just keeps playing whatever is already playing. The annoying thing is that it worked *perfectly* before the OS upgrade.
I also have a Mazda CX-5 (2016) and in that it's pretty close to the same deal, you can only control it via the iPod itself now, and about half the time you get an error that pops up on the iPod itself saying "only one device at a time" at which point you have to reboot the iPod to use it. Prior to the OS update it worked - you could control via the cars screen (although there was sometimes a few minutes delay when you started the car because it had to sync the index)
Both vehicles are completely up to date as far as firmware and software on their entertainment centers.
I am considering reverting the iPod back to an earlier OS or even rooting it... the only reason I really have it is for car music, so if it's not working in the cars... not at all concerned about security or whatever because it's just a music player (it's not logged into anything including the Apple store, iTunes, etc.) But before I do that was just wondering if folks here had similar issues and found a workaround.
I can use my phone (iPhone X) for music but I have a huge collection on my iPod and frankly just prefer the controls on the iPod (when they worked!) and occasionally find myself driving where there isn't reliable streaming coverage.