CAPTCHA Images 404 in CF2021

After upgrading to CF2021 from CF2018, CAPTCHA images stopped working in one of our environments but not the others.  As far as I can tell, they appear to be configured the same other than some additional Tomcat features being turned off in the problematic environment (mobile debugging, security analyzer, RDS, and JS debug.)  None of these features seem like they should interfere with CAPTCHA.

I can see the files being created by the CF calls in the {application_home}/tmpCache/CFFileServlet/_cf_captcha/ directory in all environments, but I'm getting a 404 error when the png images are requested by the browser.  The permissions from root down to the _cf_captcha directory appear to be the same in all environments, though.

The uriworkermap.properties file contains /CFFileServlet/* = cfusion in all instances, and I see no alias rules or other remapping in /etc/httpd/conf/httpd.conf nor the mod_jk files related to the connector that would be directing the server to look elsewhere for these files.

Thoughts on somewhere else to look for configuration differences/issues?