Why does my menu icon display as a black box?

I have a menu called “All departments”:

I am trying to match the icons to the ones on the next section where the slider is:

However once I change the icon in the all departments menu:

It then shows like this black box:

Can anyone tell me why this is happening or how I could fix it? I would greatly appreciate it.

Hi @tevinhendricks ,

Can you share your store url

Hi @zaczee ,

Yes sure https://zani.africa.com/

Password to view: Zani54321%$