I was able to regain access to my phone by temporarily disabling 2-factor authentication.

I switched the NFC Ring Unlock app to "disable." I'm not sure what changed, but after some time and a few unlock/relock cycles with the NFC Ring Unlock app disabled, it has re-enabled itself, with the same symptoms as previously. After getting back into my phone by disabling 2-factor authentication a second time, I checked and discovered that the NFC Ring Unlock app was still disabled, but was overlaying the unlock screen anyway. Admin priviledges were enabled all the way through this process.

I have now uninstalled the NFC Ring Unlock app, since it seems to be too unstable for regular use.

I'm having a problem with my NFC ring. When I turn on my phone, I enter my unlock code (my current default unlock method), then the NFC lock screen comes up. I place my ring over the sweet spot, it chirps, then nothing else happens.

How I got here:
[list=1:1dwbx3hs][:1dwbx3hs]I scanned the private side of my ring a few times[/:m:1dwbx3hs]
[:1dwbx3hs]I enabled NFC unlock[/:m:1dwbx3hs]
[:1dwbx3hs]I was always able to unlock my phone, though it took some coaxing sometimes; Normal ring + Nexus 4 is not completely reliable[/:m:1dwbx3hs]
[:1dwbx3hs]I changed my unlock method from pattern to code[/:m:1dwbx3hs]
[:1dwbx3hs]I cannot unlock my phone[/:m:1dwbx3hs][/list:o:1dwbx3hs]

A few other comments:

It is not obvious to me how to set up side-by-side unlock options. I would like to be able to unlock my phone with either my ring or my code. In part, this is necessary because I have a VPN installed on my phone, which is not allowed without a pattern, code, or password unlock.

Google 2-factor authentication is a must for me. Now that I have enabled it, I don't want to part with it. I would really appreciate a way to deal with unlocking and 2-factor.

I'm going to try disabling 2-factor authentication temporarily so that I can get back into my phone.