Hmm That’s very normal issue, we are aware of it and it does not affect the effectiveness of the app itself
We have no idea yet why Facebook shows that error, while in fact the Facebook Pixel app only loads the pixel a bit delayed in order to protect it from “zombie” traffic…
Pageview event actually, is fired every single time your page is loaded, why it’s not fired in your specific case that will need further investigation, you can PM us or share your page URL and we will check it for you