Debian Apache2（谷歌云）.htaccess密码验证失效调试求助

我知道这个话题已经被讨论过很多次，但至今没找到有效的调试方向。目前已经确认.htaccess文件会被Apache读取（添加乱码会导致网站崩溃），且.htpasswd文件已创建，但访问网站时完全没有弹出用户名和密码验证的请求，求帮忙分析如何排查问题。

当前配置细节 #

1. /etc/apache2/apache2.conf 核心目录配置 #

<Directory /var/www/>
  Options Indexes FollowSymLinks
  AllowOverride All
  Require all granted
</Directory>

2. /var/www/html/.htaccess 认证配置 #

AuthType Basic
AuthName "Área restrita"
AuthUserFile /etc/apache2/.htpasswd
require valid-user

3. 站点基础环境 #

• 无额外虚拟主机配置，为唯一托管网站的虚拟机
• DocumentRoot配置位置：

  sites-available/000-default.conf:       DocumentRoot /var/www/html
  sites-available/default-ssl.conf:       DocumentRoot /var/www/html
  

• 同时在/usr/lib/cgi-bin目录放置了完全相同的.htaccess文件，用于保护Perl脚本

4. 曾添加的访问限制指令 #

不确定是否影响认证生效，之前尝试过添加如下配置：

<Location />
    Require ip 107.217.8.189
</Location>

5. 已加载的Apache认证模块 #

执行命令sudo apachectl -M | grep auth得到结果：

auth_basic_module (shared)
 authn_core_module (shared)
 authn_file_module (shared)
 authz_core_module (shared)
 authz_host_module (shared)
 authz_user_module (shared)

6. 系统中存在的Directory容器（多为默认配置） #

conf-available/gitweb.conf:               <Directory /usr/share/gitweb>
conf-available/gitweb.conf:               </Directory>
conf-available/javascript-common.conf:    <Directory "/usr/share/javascript/">
conf-available/javascript-common.conf:    </Directory>
conf-available/serve-cgi-bin.conf:        <Directory "/usr/lib/cgi-bin">
conf-available/serve-cgi-bin.conf:        </Directory>
conf-enabled/gitweb.conf:                 <Directory /usr/share/gitweb>
conf-enabled/gitweb.conf:                 </Directory>
conf-enabled/javascript-common.conf:      <Directory "/usr/share/javascript/">
conf-enabled/javascript-common.conf:      </Directory>
conf-enabled/serve-cgi-bin.conf:          <Directory "/usr/lib/cgi-bin">
conf-enabled/serve-cgi-bin.conf:          </Directory>
mods-available/alias.conf:                <Directory "/usr/share/apache2/icons">
mods-available/alias.conf:                </Directory>
mods-available/userdir.conf:              <Directory /home/*/public_html>
mods-available/userdir.conf:              </Directory>
mods-enabled/alias.conf:                  <Directory "/usr/share/apache2/icons">
mods-enabled/alias.conf:                  </Directory>
sites-available/default-ssl.conf:         <Directory /usr/lib/cgi-bin>
sites-available/default-ssl.conf:         </Directory>

内容的提问来源于stack exchange，提问作者Marcos Camargo