Last week I got a very special mail from Mr. Keith Stroup. He recently purchased an orphaned leaf from a Flemish Book of Hours, which has a sizable portion of The Stabat Mater text scribed upon it. The leaf had been matted decades ago with the only information stating that it was scribed in Flanders ca. 1500. It begins with the last line of stanza 10: Ut sibi complaceam. It follows the Analecta version to the 20th stanza: Fac ut animae donetur. The last line Paradisi Gloria is missing. Mr. Stroup send me two pictures of the leaf.
This is the recto, or front of the leaf:

This is the verso, or back of the leaf:

Thank you very much Mr. Stroup!