Tried all possible alternatives to have the fontawesome icons displaying in the menu but can’t figure out why isn’t working!

• trying deactivate all plugins and still doing the same
• tried switching theme and still doing the same
• cleared browser cache
• used CDN instead fontawesome plugin

So what happen is that when trying to place <i class="fa-solid fa-bolt-lightning"></i> and saving, only the i tag is left… without the class <i></i>

Also trying with switching the ” to ‘ like <i class="fa-solid fa-bolt-lightning"></i> or adding the title

The result is always the same <i></i>

Tried the [] approach with [icon name="bolt-lightning" prefix="fas"] and it renders as it is

Any other alternative approach I could try?