Unable to use Xcode's "Generate Fix for Issue" feature

**Describe the bug**
I want to be able to use Xode's "Generate Fix for Issue" feature, but it doesn't work with Copilot for Xcode.

**Versions**
- Copilot for Xcode: 0.44.0 (0.44.0)
- Xcode: 26.1 (17B55)
- macOS: 26.0.1 (25A362)

**Steps to reproduce**
1. In Xcode, in the source code editor, click on a warning or error.
2. In the pop-up that opens, click **Generate Fix for Issue > Generate**

**Expected Result**
The AI suggests a fix for the warning/error.

**Actual Result**
I get this model dialog instead:

**Logs**
Copilot for Xcode does not log anything when this happens.