This is not a WordPress bug, it is a Chrome bug.
You can follow the ticket tracker here
There are a couple of workarounds to fix this until the new Chrome version arrives.
Add the follow hook via your functions.php
file or using a plugin.
Workaround 1
add_action('admin_enqueue_scripts', 'chrome_fix');
function chrome_fix() {
if ( strpos( $_SERVER['HTTP_USER_AGENT'], 'Chrome' ) !== false )
wp_add_inline_style( 'wp-admin', '#adminmenu { transform: translateZ(0); }' );
}
Source
Workaround 2
In Chrome, go to chrome://flags/#disable-slimming-paint
Enable the "disable slimming paint" setting and ensure that the "enable-slimming-paint" setting immediately below it is not turned on.
Chrome will need to Relaunch to save the setting. Once you have done so, the bug is gone.
Source