无法找到wordpress内容目录（wp-content）

I have configured my wordpress (5.0.3 -- latest) on the remote server (OS: Ubuntu 18.04).

Please find the directory structure for my blog directory. As you would notice, permissions are there so that wp-content is writable.

Following is the configuration in my wp-config.php:

define( 'FS_METHOD', 'ssh2' );
define( 'FTP_BASE', '/var/www/html/blog/' );
define( 'FTP_CONTENT_DIR', '/var/www/html/blog/wp-content/' );
define( 'FTP_PLUGIN_DIR ', '/var/www/html/blog/wp-content/plugins/' );

define( 'FTP_USER', 'ubuntu' );
define( 'FTP_PASS', 'XXXXXX' );
define( 'FTP_HOST', 'www.mydomain.com:22' );
define( 'FTP_SSL', true );

Now, when I'm trying to do any kind of write (like editing post, adding a theme, etc. I'm facing the error: "unable to locate wordpress content directory (wp-content)" while it is properly defined.

Another strange thing I noticed, while I was uploading the theme, it happened successfully in wp-content/uploads, but nothing new gets installed. Help me resolve this issue, as I have deployed wp before couple of times but this issue is something very new to me. All of the solutions available tell me to set that CONTENT_DIR in wp-config.php, which I have done from the very beginning anyway.