If I have added some items in Quick Collection and I select the item(s) in Quick Collection, then that item gets highlighted in Item Summary as well, which is very useful in case those items need to be matched off.
But if the item(s) is/are deselected or removed from Quick Collection, the same item(s) remain highlighted in Item Summary and if we try to create Manual Match, it selects all the items, even the ones which have been deselected/removed from Quick Collection.
This can result in either incorrect match group creation or user ending up removing items from Quick Collection and then additionally deselecting those items in Item Summary before manually matching them off.