Hello,
The search operators “since: and “until:” only work within the time frame of the past 9-10 days before the date of your query.
Because of the Twitter Public API restrictions, you will not get any tweets beyond this time limit.
We recommend that you check your query in the Twitter search bar and sort by “Latest” to review available data.
If you are looking for historical Twitter data, you need access to a different API which NodeXL does not provide. Here is a good article about that topic: https://gwu-libraries.github.io/sfm-ui/posts/2017-09-14-twitter-data