iPhone lightning to Car Radio - forgets last played, starts with same song!

I have a car stereo with a USB connector that plays iTunes music from my iPhone (lightning-to-USB cable) and also charges the phone. Connectivity with the phone function is via Bluetooth. The stereo, though several years old, was designed for iPhone compatibility, and used to work fine with my older iPhones and iOS versions. More recently, the iPhone no longer remembers what was last being played, but always starts playing the same song when I insert the cable. I often listen to radio apps, but if I turn off the car and turn it back on, I get iTunes playing that song - there is no ability to recall and resume the app last used for audio, or which iTunes playlist was being played. The song happens to be "Come Together" on the album "Abbey Road" - I believe this is the very beginning of my music list arranged by album, alphabetically. I don't remember exactly when this changed, but a while back, play ALWAYS used to resume with what had last been playing (same car stereo). In fact, there even seemed to be separate recall for audio via headphones, and audio via lighting connector. Am I missing a setting, or did Apple just drop this valuable feature? Thanks, JW