BackgroundMode never finishes image generation, when I edit images

[Keremk]

When editing an existing image, the backgroundMode always returns “in-progress” as response (using Responses API) and never completes. If I am generating an image from a prompt, then the background mode does complete and works as expected. In my OpenAI logs I can see that the image to be edited is uploaded, but an output is never generated. I am using Base64 encoding in the responses API. I also tried uploading a file and using its fileId and in that case I immediately get a “Failed” response from the API.