I was not aware of this problem.
Consider it registered as a bug and we will work on it.
BTW, a missing first article is a potentially nasty problem. The actual filename is stored in the first article. If this is missing, then SABnzbd has to guess the filename from the subject line. This is not a very reliable method, given the mess many uploaders make of it.
Could you email the particular NZB file to email@example.com