A Microsoft file hosting and synchronization service.
Hello NA
I understand why this is frustrating, especially when the heading navigation made OneDrive a convenient way to read longer Word documents.
Could you confirm your current OneDrive app version and iPadOS version, and whether the heading option is missing from every Word document or only certain files?
If the option is missing from all documents after updating the app, there does not appear to be a documented setting for restoring it in the OneDrive viewer. For now, opening the document in Word for iOS may be the only available workaround.
You can also report the missing functionality from OneDrive > Me > Help & feedback, which sends the feedback to the relevant product team.
Feel free reply back to this post, I look foward to your update.