.prependParagraph() not respecting frontmatter

In this note:

---
title: Filer TEST destination
tags: #test
---
## Project Tasks (H2)
* Existing task
...

When running note.prependParagraph("new task", "open")` I'd expect to get:

---
title: Filer TEST destination
tags: #test
---
* new task
## Project Tasks (H2)
* Existing task
...

But instead I get

---
* new task
title: Filer TEST destination
tags: #test
---
## Project Tasks (H2)
* Existing task
...

I.e. it isn't respecting the fact that there is frontmatter.