[BUG] No sample questions showing

[JoonYong-Park]

Describe the bug
When selecting certain benchmark categories (e.g., English, Science, Knowledge), the sample questions do not appear. Instead, it shows an empty state message saying "No sample questions found for this combination."

Steps to reproduce

1. Select benchmark categories (e.g., English, Science, Knowledge).
2. Check the sample questions preview section below.
3. See the "No sample questions found" message.

Expected behavior
Sample questions relevant to the selected categories should be displayed.

Screenshots