New Target list from Campaign does not include last entry

We have a problem when trying to create new Target List from ex: Opt-Out subpanel in a Campaign it creates the target list but the last entry inside is not added to that new list.

I have found that when i set the


$sugar_config['disable_count_query'] = false;

the whole exporting to new target list works and includes the last entry.

So my question is, is it a problem to use ‘disable_count_query’ on false (does it impact performance) and is there another way of fixing the problem above ?