DOC items have a specific document filter field where you can select a filter for the document downloaded.
These filters can be negated by double clicking
If you have selected such a filter, the Download document button will indicate this by warning symbol, because the downloaded document will not indicate which labels have been used, but just filter the items shown.
Note: when you download such document with a filter enabled, the download progress bar won't be green but will appear in orange:
If you want to exclude some items from a document when they have a specific label, you can double click on the filter box. It will say "NOT xxx"
and the document will exclude the items that do not have that label set (for the categories where the filter applies).
When a DOC item has a document filter set, and a SIGN item is created from this the SIGN item will take the filter into account.