Cannot login (ignores credentials)

I have a client who cannot log into his website, although I still can (as the webmaster).
I have researched this topic extensively in this forum but have not found a similar case.

The symptom first started as after inputting his username and password, nothing happens; the screen flashes and returns, with the username and password fields empty. I have turned on debug mode in a staging copy. We tested turning off each one of the 9 plugins individually and trying to log in — no change. I called into tech support for the hosting platform (Siteground), and the tech could not see anything in any logs indicating abnormal responses.

A couple of days later, the symptom changed to an ‘Access Denied’ screen, which is apparently coming from the hosting platform, and this user cannot even get to the login screen.

We are running WP version 5.8, PHP version 7.3.29. We have 9 plugins total, and 3 of them have to do with security (the most likely ones to interfere with a login): Securi, Wordfence and Loginizer.

I was able to inspect the debug log to find where this user tried to log in:

67.161.158.132 staging3.colivableclimate.org - [27/Jul/2021:10:40:16 +0000] "GET /wp-login.php?action=rp&key=cYirdWVN891QEjyHjTXr&login=kcross HTTP/2.0" 302 0 "-" "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/92.0.4515.107 Safari/537.36" | TLSv1.3 | 0.641 0.661 0.661 BYPASS d NC:010000 UP:SKIP_CACHE_SET_COOKIE

Can anyone tell me if this says anything helpful, or what else to look for in the debug log, or if you have ever experienced similar behavior?

Thanks for any help,
Rick

• This topic was modified 4 years, 8 months ago by Jan Dembowski. Reason: Moved to Fixing WordPress, this is not an Everything else WordPress topic

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