Allow admins to login as other users

You’ll need to find out what specific capabilities Admin users are missing. Once you know the full list, you can use add_cap() to add those capabilities to the Admin users and enable them to do whatever the other roles are doing.

From Shold I manually add ‘cap’ to admin role ? –

$role = get_role( 'administrator' );
$role->add_cap( 'cap' );

Replace cap with one of the capabilities you need to add to admin users. Copy and paste that second line, and add each additional capability separately.