Facebook Pixels?

Recently Facebook had not been logging my conversion events on their platform - even though the events and pixel triggered whilst testing.

I was using their recommend Events set up via URL listening.

So I fixed it by hard coding the pixel.

The problem was that during this issue, my ads were running and still making sales (not the problem) but because the purchase events were not tracking- my CPA went sky high.

Now after testing the new campaigns (outside of the high CPA campaigns) I have noticed a considerable drop in performance and an increase in CPA plus at a lower volume

In fact the CPA is almost 10x the average account wide CPA.

So for me, I've never seen these CPAs in the two years I've been running the account.

Any ideas what I should do?

Should I warm up a new pixel and start again, or is this just a coincidence?

In your case I would recomment to create a new pixel, warm it up and start from the beginning.