Plugin works occasionally

Hello!
We have a problem with plugin. It works just occasinally. Sometimes main page is available, sometimes it’s blocked by plugin. Logs are showing that all this attempts was blocked, but it was available for user.
We blocked only front-end with a 500 Internal Server Error response code.
Using the block by country mode for all requests.
Need your help! Thank you in advance!

Diagnostic info
– Server: Apache
– MySQL: 5.6.39-log
– PHP: 7.1.25
– PHP SAPI: fpm-fcgi
– Memory limit: 128M
– Peak usage: 50.64M
– WordPress: 5.0.3
– Multisite: no
– File system: direct
– Temp folder: /tmp/
– Process owner: wp_sapbh8
– File owner: wp_sapbh8
– Umask: 755
– Zlib: yes
– ZipArchive: yes
– PECL phar: yes
– BC Math: yes
– mb_strcut: yes
– OpenSSL: yes
– SQLite(PDO): yes
– DNS lookup: available [108.0 msec]
– User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.14; rv:64.0) Gecko/20100101 Firefox/64.0
– Storefront 2.4.2
– DreamHost Panel Login 1.0.0
– Elementor 2.4.0
– Google Analytics Dashboard for WP (GADWP) 5.3.7
– IP Geo Block 3.0.17.3
– Jetpack by WordPress.com 6.9
– My Custom Functions 4.32
– Popup Builder 3.1.5.2
– Proxy Cache Purge 4.7.3
– Storefront Blog Customiser 1.2.5
– Storefront Footer Bar 1.0.4
– Storefront Mega Menus 1.6.2
– Storefront Powerpack 1.4.13
– Storefront Pricing Tables 1.1.0
– Storefront Product Hero 1.2.13
– Verotel/CardBilling/Bill/GayCharge/BitsafePay FlexPay for WooCommerce 1.5.3
– WooCommerce 3.5.3
– WooCommerce Amazon S3 Storage 2.1.10
– WooCommerce Blocks 1.2.0
– WooCommerce Google Analytics Integration 1.4.7
– WPForms Lite 1.5.0.4
– Yoast SEO 9.4