Once the invoice is in the Processing status, it becomes clickable. You can choose to manually fill out the required data (these are marked with an asterisk and appear in red) given the mechanical part of the data recognition (OCR) has been completed.
That way, you don't have to wait for the final OCR result. This comes in handy when you need to forward an invoice to your accountant as quickly as possible. The document will then no longer be in the status 'To be accepted' but will immediately be forwarded to your accountant or bookkeeping if they are linked.