I’m running these on an iPhone 6 with iOS 12.4.
Sony app version 5.2.0.
I can test these on an iPhone 7s on the latest iOS this weekend if that helps.
Thanks @delta0 I tried this on my sons iPhone 6 (12.4) and installed the Sony Connect 5.2.0 and it did the same thing, so maybe the earphones are faulty, if anyone else can confirm I'd be grateful