I'm passing in kSecAttrAccessibleWhenUnlockedThisDeviceOnly. But I've thought that could be the cause* and also tried kSecAttrAccessibleWhenUnlocked, kSecAttrAccessibleAfterFirstUnlock and even kSecAttrAccessibleAlways. The issue exists no matter what the protection is.
*since all the Macs that exhibit the issue are on 10.12 but also don't have a Secure Enclave (Intel Macs without T1 or T2 chip).
I've also just filed FB12189765. There's a sample project attached to the feedback. I can't seem to attach a zip here but I'm attaching the relevant code as a .txt for reference here.
ContentView.txt
Topic:
App & System Services
SubTopic:
Core OS
Tags: