My Apple Watch has stopped unlocking my Mac, what trouble shooting steps should I take? Updated.

My Apple Watch has just started unlocking my MacBook Pro again! Since I posted back in January that I was unable to unlock my Mac using my Series 3 Apple Watch, all efforts to resolve this issue failed and I disabled the Security & Privacy setting. This morning, having updated watchOS to 7.5, I find that the feature is not only enabled again (I don't remember doing this, though...) but is also working as it always used to. My Mac is still on Mojave 10.14.6. In the same way that I don't ever remember changing anything on my Mac that caused the feature to stop working, I don't recall changing anything recently to cause the feature to start working again. My conclusion? Was there a bug in watchOS? Who knows, but I am thrilled to report that the issue is resolved!