Firefly Upscaler in Photoshop 27.10 creates a solid black result on macOS

I am experiencing a reproducible issue with Generative Upscale in Photoshop 27.10 on macOS.

When I use Generative Upscale > Firefly Upscaler, the resulting document is created, but the image is completely black.

Steps to reproduce

1. Open an image in Photoshop.
2. Choose Generative Upscale.
3. Select Firefly Upscaler.
4. Run the upscale.
5. The result opens as a solid black image.

Expected result
The upscaled image should be displayed normally.

Actual result
The resulting image is completely black.

Important details

• Partner models such as Topaz work correctly inside Photoshop.
• Firefly Upscaler works correctly in the Firefly web app.
• The problem occurs only with Firefly Upscaler inside Photoshop.
• I tested with sRGB, RGB color, and 8-bit images.
• I reset the Photoshop preferences completely.
• I signed out of Creative Cloud and signed back in.
• None of these steps fixed the problem.

The UXP log repeatedly shows errors related to the newly created document:

handleNewDocument: activeDocument null

handleNewDocument: doc 64 not yet queryable, queued for deferred retry

[CAI:handleNewDocument] timer retry: doc 64 not yet available

The same behavior occurred multiple times with different document IDs.

Photoshop version: 27.10.0

This appears to be an issue in the Photoshop desktop integration with Firefly Upscaler, because the same Firefly Upscaler works normally in the web version and partner upscalers also work normally inside Photoshop.