There are some KBs/threads on this. Please check below.
I checked all of those articles before posting. Those articles cover issues like log settings not correct, changing time on the firewall, license not properly applied, et cetera. None of those explanations apply here. None of those explain why logs would suddenly stop writing after 6 years of continuous logging without incident. However, this is very curious. After about two hours, the logs showed up. One of my other admins witnessed it. Very strange.
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