While processing a document with FlexiCapture it cannot be matched with Document Definition and receive unknown document status even though the very same document was correctly matched in FlexiLayout Studio and the layout was successfully uploaded into FlexiCapture.
Also, while forcing the matching none of the fields were captured.
It might happen if the data required for matching is stored in the image inside the document. Usually, it happens with PDF files. The required information is absent in the text layer.
In this case, please, use the "OCR only" option in the related Batch Type Properties -> Image Processing -> Processing of PDF:
This will allow the extraction of the data from pictures and help match sections.
Also, you might need to use the mentioned option in the Project Properties or related Image Import Profiles depending on your setup.