RTF formatting reverting or disappearing upon save

I am in the process of making chapter summaries of the books I read by creating a new RTF document per book, using a numbered style for chapters, notes in one paragraph per chapter. This used to work seamlessly, but recently does not. The chapter numbers appear as they should while working on the document but disappear when I save or close the document. The paragraphs remain paragraphs, but without numbers.

If I open the document in TextEdit the numbered list appears as intended. What is happening?

Devonthink 4.2

macOS 26.2

See Bullets Formatting Not Showing