After troubleshooting, I found that the issue was due to configuration settings.

-Steps to Fix the Sub-Category Slider

1. Enable the Sub-Collection Display in Theme Settings Navigate to Admin Panel → Stores → Configuration. Under Theme Settings → Category, ensure the following: Show Sub Collection → Set to "Yes". Ratio Sub Collection → Set to 1.
2. Verify Parent Category Settings Go to Catalog → Categories, then:

Select the parent category containing the subcategories. Check the following settings: Category Thumbnail → Must be set (image should exist). Display Mode → Set to "Static block and products". Ensure there are products assigned to the category. 3. Ensure Subcategories Are Properly Configured For each sub-category, verify:

Use Parent Category Settings → Set to "Yes". Ensure the subcategory is enabled and has products. the result is