You're very fortunate that Pioneer actually does updates for their receivers. Many manufacturers simply don't....it's pretty rare.seems to be problem with bluetooth/usb or the way iOS11 works
try turn bluetooth completely off (in setting) before connecting usb cable. Otherwise, update the head unit
I have a Pioneer X8650BT on my car. It used to work fine with iOS10. The other day I updated my 6S to iOS11 and it stopped working completely (plugged cable in and nothing happened). Problem is solved by updating the head unit's firmware (took freaking 8 hours)
Hyundai/Kia has a wholly owned subsidiary called Modis that makes some of their receivers. Notorious for never doing a firmware update after they're shipped. (it's why I put an Alpine in mine) - but even them, being solely a CarPlay deck, there's been issues with iOS 11.
@happyslayer - best advice I can give is to find out how to get into the setup screens for your decks and find enough information to be able to google which manufacturer it is that actually made your receivers. Then you can follow up with the manufacturer and see if they have any firmware updates.