See if you are able to access/list the '/icons/' directory. This is useful to test the behavior of Directory in Apache.
for eg : You might be having below config by default in your httpd.conf file.So hit the url : IP:Port/icons/ and see if it list the icons or not.You can also try by putting the 'directory/folder' inside the 'var/www/icons'.
Alias /icons/ "/var/www/icons/"
Options Indexes MultiViews
AllowOverride None
Require all granted
If it does works then you can crosscheck or modify your custom directory configuration with '' configuration.