I'd like to, but the header still contains information that I am contractually obligated not to share. I did however find a solution. If I copy and paste a header from secondary document into the original header, it allows me to edit it after that. It is still a strange problem.

Some background, the document was sent off for translation and the translators may have used a different version of Word to complete the task. I'm assuming it is some kind of corruption issue. Just a thought. Anyways, thanks for taking the time to respond, but I have found a workaround.

From where did the content of the "problematic" header originate? If it was created by a field, the field (or the location it references) could be damaged.

To work around corruption, you can usually copy all the content minus the final paragraph mark (¶) of the document into a new, blank file. Note that if the document contains section breaks, you will have to copy each section separately (and omit the section breaks).

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Stefan Blom
Microsoft Word MVP

Microsoft 365 apps for business
Windows 11 Professional