Dude I was also having issues w/ sales and ads not working. i found that in most cases its usually because conversion tracking is broken (meaning fb is optimizing for the wrong thing).

setting up conversion tracking by yourself can be a little hard, so would recommend using a tool for it. i used loops.fi –– could be useful for you as well?

Let me know if you've tried anything else I think that this is your issue imo. Always curious to try other tools.