Approvals in a SharePoint document library

Below are the possible reasons and fix:

• Automatic metadata updates from sensitivity/retention labels, compliance policies, or DLP rules
• Thumbnail/previews or search-indexing processes that rewrite file properties
• The OneDrive sync client re-uploading changes to the file
• Any Power Automate flow or script writing to the item, even to a “hidden” column

Because none of these bump the major version, you won’t see an entry in Version History but the approval request is cancelled all the same.

To fix:

• Review and scope your auto-labeling or retention policies so they don’t apply to this library (or turn them off temporarily).
• Disable OneDrive sync for that library (or exclude the folder).
• Audit any flows or event receivers that write metadata back to items.
•  If you need approval to survive metadata changes, replace the built-in approvals with a Power Automate approval flow those won’t reset on metadata edits.