My custom functions in “functions.php” doesn’t work.
Normally, you can add code snippets for your custom functions into functions.php which is placed in your theme or child theme folder. But in case you select “mu-plugins” (ip-location-block-mu.php) as “Validation timing” in “Validation rule settings” section, your code for this plugin in functions.php would be failed to work as you expected.
This restriction is originated from the excution order described in Action Reference where you can find muplugins_loaded action hook is triggered far before after_setup_theme which is the timing of your functions.php to be parsed.
Then what’t the solution?
Installing “drop-in.php” and "drop-in-admin.php"
To install, upload drop-in.php or drop-in-admin.php in /wp-content/uploads/ip-location-block/dropins/
You can find a sample for drop-in.php in /wp-content/plugins/ip-location-block/wp-content/drop-in-sample.php. Just rename it to dropi-in.php and upload in the directory mentioned above.
Both drop-in.php and drop-in-admin.php are similar but are fired on different sides. The first is used on the front-end and the second is used on the admin side.
Note that even in the case of multisite, drop-in.php and drop-in-admin.php will be called on every site. So if you want each site to behave differently, you should add some code like follows:
<?php
/**
* Drop-in for IP Location Block custom filters
*
* @package IP_Location_Block
* @link https://www.ipgeoblock.com/codex/#filter-hooks
* @example Use `IP_Location_Block::add_filter()` instead of `add_filter()`.
*/
if ( ! class_exists( 'IP_Location_Block' ) ) {
die;
}
$components = parse_url( site_url() );
switch ( $components['host'] ) {
case 'example.com':
if ( 0 === strpos( $components['path'], '/subdir1' ) ) {
// here is code snippet for sub directory 1
}
elseif ( 0 === strpos( $components['path'], '/subdir2' ) ) {
// here is code snippet for sub directory 2
}
break;
case 'subdomain1.example.com':
// here is code snippet for sub domain 1
break;
default:
// here is code snippet for default
break;
}functions.php doesn't need to be put together into drop-in.php but functions related to only this plugin such as Filter hooks for this plugin.
In this case, check your country code and configure properly on Settings tab: 
Or check whether your IP address is blacklisted: 
In this case, remove your IP address from the cache on Statistics tab: 
In this case, please try to deactivate IP Location Block once and re-activate again to re-install Geolocation API libraries on Plugins page.