get_drawings not working on Figure 2 in ChemRxiv paper

[jamesbraza]

In the paper "A Perspective on Explanations of Molecular Prediction Models":

• Link: https://chemrxiv.org/engage/chemrxiv/article-details/639222a114d92d7cd6a65e90
• PDF: https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/639222a114d92d7cd6a65e90/original/a-perspective-on-explanations-of-molecular-prediction-models.pdf

With Python 3.13.2, pymupdf==1.26.3, pydantic==2.11.7 and the following Python code revolving around page.cluster_drawings(drawings=page.get_drawings()):

import pathlib

import pymupdf
from pydantic import BaseModel, Field, JsonValue

THIS_DIR = pathlib.Path(__file__).parent


class ParsedImage(BaseModel):
    """Raw image parsed from a document's page."""

    index: int = Field(description="Index of the image in a given page.")
    data: bytes = Field(
        description="Raw image, ideally directly savable to a PNG image."
    )
    info: dict[str, JsonValue | tuple[float, ...] | bytes] = Field(
        default_factory=dict,
        description=(
            "Optional image metadata. This may come from image definitions sourced from"
            " the PDF, or attributes of custom pixel maps."
        ),
    )


content: dict[str, tuple[str, list[ParsedImage]]] = {}
with pymupdf.open(THIS_DIR / "a-perspective-on-explanations-of-molecular-prediction-models.pdf") as file:
    for i in range(file.page_count):
        page = file.load_page(i)
        images: list[ParsedImage] = []
        for box_i, box in enumerate(
            page.cluster_drawings(drawings=page.get_drawings())
        ):
            pix = page.get_pixmap(clip=box, dpi=150)
            images.append(
                ParsedImage(index=box_i, data=pix.tobytes(), info={"bbox": tuple(box)})
            )
        content[str(i + 1)] = page.get_text("text"), images

# Save all images, to make review easier
output_dir = pathlib.Path(__file__).parent / "extracted_images"
output_dir.mkdir(exist_ok=True)
for page_i, (_, images) in content.items():
    for image_i, image in enumerate(images):
        with (output_dir / f"paper_page{page_i}_image_{image_i:03d}.png").open(
            "wb"
        ) as f:
            f.write(image.data)

assert "Figure 2" in content["8"][0], "Expected page 8 to be about Figure 2"

The Figure 2 diagram is not properly extracted, actually it's not present at all.

Is this a bug in page.get_drawings?