I recently purchased a 2014 IS 250 and have had quite a bit of trouble with the bluetooth connectivity with my iPhone 8. The phone will show as connected, but will play music through my phone versus the car audio. I have found a few workarounds such as pressing the play/pause button on the car a few times, but it is pretty aggravating. Initially Lexus thought it was a radio problem and replaced the entire system, but I still continued to have problems. I have spoken to both Apple and numerous people at Lexus and they basically said that there was nothing they would do unless the problem was widespread. I am fairly certain there needs to be a firmware update to adjust to the new software on phones. If you have had this same or a similar problem, please comment below.

 

The usual suspects in your case are:
Q) Do you have an Apple Watch or FitBit paired to the iPhone?
A) Try unpairing the extra component through a couple of drive cycles.
Q) Are other phones paired to the IS and you trade off driving?
A) Turn off the BT setting in any other phone(s) in the car

Completely unpair the phone from the car and car from the phone.
If your IS has Navigation, change the name in Setup/Bluetooth from
the default "Car Multimedia" to anything distinctive, ie. Lexus IS250.
When repairing your iPhoneXIII be certain that the new banner in the
phone changes to reflect the proper name before tapping it to pair.
If you jab at the first banner that pops up it can cause some sort of
incomplete pairing, works but badly...