[users@httpd] Why Apache does not save some records to error log

[Анатолий Кирсанов]

I am not sure what is the reason of my problem. In some cases my PHP 
script successfully saves data in it's own (script's) log. But there is 
no corresponding record in Apache access log.
Why?

The error log is empty.
*
mod_fcgid/2.3.9
Apache/2.4.6 (CentOS)
PHP 7.1.3
Apache config*
<VirtualHost 127.0.0.1:8080>
    ...
        CustomLog /var/www/httpd-logs/example.com.access.log combined
        ErrorLog /var/www/httpd-logs/example.com.error.log
     ...
        <FilesMatch "\.ph(p[3-5]?|tml)$">
                SetHandler fcgid-script
                FCGIWrapper /var/www/php-bin-isp-php71/user/php
        </FilesMatch>
    ...
</VirtualHost>

*PHP 7.1 config*
error_log empty (not set)
log_errors on
error_reporting E_CORE_ERROR | E_ERROR | E_COMPILE_ERROR | E_PARSE