[macOS] Language selector missing Simplified Chinese in ChatGPT app (region-dependent issue?)

Summary

The ChatGPT macOS app does not provide an option to switch the UI language to Simplified Chinese. This appears to be a regression or region-dependent issue introduced in recent versions.

Environment

• macOS: 26.4.1
• ChatGPT app: 1.2026.098 (1776453807)
• System language: Simplified Chinese
• System region: Hong Kong SAR
• App Store region: United States
• Current IP location: United States

Reproduction Steps

1. Launch ChatGPT macOS app
2. Navigate to Settings → General → Language
3. Attempt to change UI language

Expected Result

Simplified Chinese should be available as a selectable UI language.

Actual Result

• Simplified Chinese option is not present or
• Language setting does not affect UI language

Observations

• The web version of ChatGPT supports Chinese normally under the same account
• Multiple users are reporting the same issue after recent updates (community reports)
• Issue persists after restart and re-login

Hypothesis

The app may be prioritizing region (App Store / system region / IP) over system language when determining available UI languages, leading to Simplified Chinese being hidden in certain region combinations.

Impact

This significantly affects usability for Chinese-speaking users, especially those using macOS desktop as their primary client.