MY2000

Thank you bi-wan-kenobi,
I found one, called ‘author and post statistic widget’, this helps me to show most popular author’s activity on a widget. However I still searching for a plugin to be able live-time monitor my authors activity.
# Who is online
# What do they on this moment
# How much disc space they use (db and media)
# How many posts and comments they do per day
# What posts/pages they visit in my site
# What browser they use
# Activity log (for example: user X just changed his password)
# and so on….

Ok, put this in your wp-config.php and it’ll start working

define('WP_HOME','https://example.com');
define('WP_SITEURL','https://example.com');

Don’t forget to change “example.com” to the current WordPress path

You should deactivate it one by one and check the issue after each plugin deactivation, and you’ll find the plugin which cause this problem. If all plugins are good, then the reason is your current theme.

Have you tried to deactivate all plugins and use the default WordPress theme?