Initiate Checkout event not firing on FB pixel

[Faham]

Hi everyone. So on my Shopify store https://www.swagkids.pk/, I have set up my FB pixel through the app Facebook And Instagram. Now when I am trying to create FB pixel events using the event setup tool I was able to do that except for/ the Initiate Checkout event. So when I go to my checkout page the event setup tool just keeps on loading and doesn’t allow me to create that event there. I have attached the screenshot too. Some experts could help me, please