Thanks for the prompt reply. We have tried your suggestion, the problem is that we end up with a lot of misclassifications for the forms with the filled field (classified as document with unfilled field) and this is worse than having a few unfilled fields with garbage. I guess this is to be expected since the "two" types of document are almost identical. And we actually have more samples with the filled field than otherwise...
Anyhow in a template model I can understand how the absence of content in a field may lead to extraction of contiguous text, but not to extraction of text from unrelated locations in the document. We will submit feedback in the Studio as suggested but we would appreciate if this could be scaled up to the responsible team.