Ok, so I have just read this from September all the way through to now. I have this issue, I have a Sony xav-ax4050 with wireless apple carplay. It is fitted into a 2008 Alfa Romeo 159, Siri did work, worked fine for me for weeks, then poof! Listens, selects the contact, starts to transcribe the message then I get a ring of dots and then after 30 seconds "Something went wrong, please try again later". I have done everything from resetting, using beta's and even buying a new phone which resolved it for about 30 minutes. Interestingly, I now have an Apple watch Ultra 2, Siri is faultless on this apart from when the phone is connected to Carplay, now if I push the crown to summon Siri and send a message, I get the same experience through my watch. I am now so convinced that this isn't Sony, or my older car but specifically the OS, also I am in the UK so interesting to rule out regional issues.
So my question is, the developer beta for iOS 18 is out, has anyone tried this and have they had any results regarding this issue?