Does "Not In" Filter exclude empty values?

yes, using not in filter always excludes (filters out) all the empty (null) values this configuration, inherited from the standard sql practice, determines that when comparing an empty value to any other value, it is neither equal nor different, but indeterminate therefore, empty values are never included when using an "in" or "not in", because it's never going to be "equal" or "distinct" restrictively to the values provided let's see it with an example we are working with this table true 220,220,221left unhandled content type left unhandled content type left unhandled content type left unhandled content type left unhandled content type left unhandled content type left unhandled content type left unhandled content type left unhandled content type left unhandled content type left unhandled content type left unhandled content type left unhandled content type left unhandled content type left unhandled content type if we create a selection and do the following filter the outcome will be true 220,220,221left unhandled content type left unhandled content type left unhandled content type left unhandled content type left unhandled content type left unhandled content type as you can see, id 4 will be excluded, because it's empty if we want to keep empty values as well as values distinct to belgium and france, you will need to add another filter that explicitly includes empty values example in this example, the outcome will be true 220,220,221left unhandled content type left unhandled content type left unhandled content type left unhandled content type left unhandled content type left unhandled content type left unhandled content type left unhandled content type left unhandled content type