I’ve had that happen, especially with ground beef. The part that is out of the liquid doesn’t look too appetizing but it will be fine! There is still a vacuum in there.
About halfway up should be good for adding water or broth. You definitely don’t want any more than that!
One thing I really love about canning meat is the delicious stock that I get along with the meat. I usually plan on soup after opening the jar. Something about the pressure canning brings out all the flavor.
Thanks!
Halfway sounds about right.