In /frontends/php/include/classes/pagefilter/CPageFilter.php in function _getProfiles() we have following code:

$profileSection = $this->config['individual'] ? $page['file'] : $page['menu'];
$this->_profileIdx['groups'] = 'web.'.$profileSection.'.groupid';

we are using global $page variable to prepare idx for profile entry.
In newer pages, where we are using MVC approach (like, Monitoring->Web), $page variable is not used any more, as a result selected age filter is saved in Profiles table with following idx:

web..groupid

As this task, usage of $page variable should be removed from CPageFilter class.

I suggest it to be done by removing ['config']['individual'] option and introducing a new one with explicit name for $profileSection that is passed in each place, where CPageFilter is used.