Answer
Situation:
I go to the Protect tab, choose the option "Mark for Redaction>Text&Images" and select the contents that I want to redact. However, when I try to select the "Apply Redactions" button under "Mark for Redaction", it is grayed out (disabled). In short, even though I have already selected the contents that I would like to redact in Foxit PDF Editor Pro, the "Apply Redactions" option is still grayed out.
Possible cause:
This issue is likely related to the specific document you are working on. If the document is a digitally signed PDF file, it cannot be modified anymore, which is why it is not possible to apply redaction to this type of PDF file.
To determine if a document has a digital signature, you can view it in the signature panel, as demonstrated in the screenshot below:
To check whether the "Modify Document" is allowed or not allowed in a PDF file, please refer to the following screenshot:
If your document is not a PDF file with a digital signature included, but you are still unable to apply redaction, please share the original PDF file with the Foxit support team for further analysis. You can submit a ticket by clicking here and attaching the file.