Trouble hatching Muscovy ducks

[pawtraitart]

Okay, so my first few hatches of the season went fine. Now, however, my muscovy eggs are going all the way to lockdown and then die when they pip on the UNDERSIDE of the egg instead of into the aircell and facing upwards. I haven't changed anything, so I'm not sure why this has started to happen to my hatches. Any ideas?

 

[Amiga]

I am not a hatcher, but just wondered if you are getting all your eggs from the same ducks(s)? Is it late enough in the season that something may have changed with the ducks that lay?