Apache 2.4 RewriteMap never matches - apache

Question

I'm using an Apache RewriteMap to permanently redirect 60 or so urls. In one development environment, the below configuration works flawlessly while in another development environment it doesn't work at all. Most notably, the last RewriteCond never passes and unfortunately the logging options I've attempted are no help. With LogLevel debug rewrite:trace8, I can see that the RewriteCond just before the map is receiving the expected input, but the map nonetheless returns no match:
[Thu Apr 19 19:35:19.109789 2018] [rewrite:trace4] [pid 11188] mod_rewrite.c(470): [client 127.0.0.1:62369] 127.0.0.1 - - [server.dev/sid#7f7719da0d50][rid#7f7719fc8000/initial] [perdir /html/path/] RewriteCond: input='/help_center/help_center.php?' pattern='^/?(.*[^\\?])\\??/?$' => matched
[Thu Apr 19 19:35:19.109793 2018] [rewrite:trace4] [pid 11188] mod_rewrite.c(470): [client 127.0.0.1:62369] 127.0.0.1 - - [server.dev/sid#7f7719da0d50][rid#7f7719fc8000/initial] [perdir /html/path/] RewriteCond: input='NOTFOUND' pattern='!NOTFOUND' [NC] => not-matched
For debugging purposes I've simplified things to pass a constant key into the map, but the map nonetheless returns no substitute value. I've also tried simplifying the map file, adding all the possible variations of a key it could receive (with and without leading/trailing slashes and ?). I've tried renaming the map file and extension, renaming the map itself, moving the map file outside of the public directory, all with no change in results. The map file is readable as is the directory it's in, Apache starts up error-free with the config and yes I've been restarting it when testing config changes.
What's left to try? Both systems run CentOS 7, Apache 2.4, one works and one doesn't. Configs below
Apache server-level config declaring map
RewriteMap help_center txt:/path/to/rewritemap/help_center.map
.htaccess
RewriteEngine on
RewriteCond %{REQUEST_URI} !(\.(js|css|less|png|swf|flv|jpg|svg|ico))$
RewriteCond %{REQUEST_URI}?%{QUERY_STRING} ^/?(.*[^\?])\??/?$
RewriteCond ${help_center:%1|NOTFOUND} !NOTFOUND [NC]
RewriteRule ^.*$ /${help_center:%1}/ [QSD,L,NC,R=301]
Abbreviated contents of help_center.map
help_center/help_center.php help-center
help_center/help_center.php?1_7_q-1 help-center/article/authorized-dealer
pages/appliance_installation help-center/article/installation-services
UPDATE
After 6 hours of debugging, I've finally been able to get the RewriteMap to match. By moving the RewriteMap directive to the <VirtualHost _default_:443> scope of /etc/conf.d/ssl.conf, urls are rewriting as expected.
Why is this the case?
The config between these two environments is very similar with the exception of virtual hosting. Both environments run SSL and redirect all requests to the SSL site. The environment that works is configured without a name based virtual host config (i.e. one site for the server) while the environment that didn't work is running name based virtual hosting. I have a single hypothesis related to this:
While I'd expect the root directive to apply to the default site and all virtual sites (including SSL), perhaps the RewriteMap directive must be virtual host scoped to be referenced by a virtual host. Not sure this makes sense, but I couldn't find any documentation to clarify. After testing, turning off NameVirtualHost nothing changes :/
Related: It seems that referencing a non-existent RewriteMap logs no error. Perhaps it was buried while I had debug logging turned on, but is there a config for logging RewriteMap reference errors? That would have help narrow my debugging much sooner.
Finally, for examining parsed Apache config run this from command line: httpd -DDUMP_CONFIG -k start or to view in vi httpd -DDUMP_CONFIG -k start | vi -. I was able to use this to confirm that my RewriteMap directive was being loaded despite it still not matching.

Answer 1

I'm not entirely sure this should qualify as an answer, but I THINK this is what has made it work: Remove the QSD argument and append a ? to manually discard it. This change was made because we have a server running 2.2 that would error out entirely (rather than not match) and it seems that a side effect is that our 2.4 servers are now matching. I'm sure not it's Voodoo, but unfortunately I can't explain it with confidence.
## QSD not available in apache 2.2, add a ? to the end of the rewrite to discard
RewriteRule ^.*$ /${help_center:%1}/? [L,NC,R=301]