"Last / Next Category" icon broken in challenges menu

**Describe the bug**
The icon doesn't represent the category it refers.

Also, a category added to the last position will have strange effects, such as Escalation Track 2 doesn't show a 'next category' image when you have one.

**Additional context**
![image](https://github.com/user-attachments/assets/58e8c197-2236-4817-b684-8f8cdf76ce5e)