Sometimes it happens that the integration worked well but suddenly stopped. It can happen for many reasons. Facebook updated the API or something else. 

The easiest way is to create a new Way.

If that doesn’t help, you need to reconnect the Facebook lead ads app.

It's something similar to a smartphone or laptop. If it's glitchy, you just reload it, and it works.

If you see a message like this in the Errors tab, it means you need to reconnect the Facebook lead ads app.

Message: (#100) App is not installed: 307386776504128. Type: OAuthException. Code: 100. Fbtrace_id: AkVsJceKoxRL0N6MFNZkK5r.

If that doesn't help either, disconnect Facebook lead ads and reconnect the app.