If you have purchased any of the following Pro2 lightning to audio leads, please note that Apple has broken compatibility with the iOS 10.3 and 10.3.1 updates.
More information can be found at: https://discussions.apple.com/thread/7910347?start=0&tstart=0
The adaptor leads affected are:
- IPLT35 LIGHTNING TO 3.5MM ADAPTOR
- 8P35S LIGHTNING TO 3.5MM SOCKET LEAD
- 8P35B LIGHTNING TO 3.5MM SOCKET LEAD
Unfortunately, the only solution at this stage is to downgrade to 10.2 and below.
NEW NOTE - Since this article was originally published, there are newer products which are compatible with Apple's MFI system.