Microsoft Graph OneNote API — PATCH content fails on any page containing a table

Question

PATCH /me/onenote/pages/{id}/content reliably fails with error 20137 ("This page can not be PATCHed") for every page that contains an HTML <table> element anywhere in its content — including brand-new pages created moments earlier via POST /me/onenote/sections/{id}/pages. Pages with no <table> (plain lists/paragraphs) PATCH successfully every time. GET, POST (create), and DELETE all work normally regardless of table content — only PATCH content-update is affected.

This was working normally through Friday, 2026-08-21 (multiple successful PATCH writes that evening). It started failing Saturday, 2026-08-22 afternoon and has not self-resolved as of Monday, 2026-08-24 evening — roughly 48+ hours of continuous failure across many pages, including ones created fresh during troubleshooting today.

This appears to be an account-level or backend regression in how PATCH content-update requests are processed for table-containing OneNote pages, not a client-side or permissions issue (confirmed via the isolation tests above). Requesting investigation into why PATCH is failing specifically for table content on this account, and a fix or ETA.