I seem to be losing quite a few animals....what am I doing wrong

Offset jaws with a good catch circle? Front footed coons. buy closed jaw traps if you can. If it is just a snapped trap pulled tight once with no catch circle, then deer are stepping in your traps. ease up on using pee or lure with alot of pee in it. Other than that your critter should be waiting for you in a 550. Unless you need new springs.

If no circles, deer.

I know which ones are deer....I've had 3-4 that made a lap or 2 and out

Check your pan level. I had that problem with them when I first got some. The pan on a little more than half was pointing up when set. Caused poor catches and pull outs.

Sounds like rollers .

X2

All my MBs are set at 3 lb. pan pressure. Pull outs not a problem. Plus step down sets can help.

Sounds like coon to me. Traps with wide offsets won't hold coon unless you catch them well above the foot.

Any blood?

This has been my experience. Every time I find a 550 set off with nothing in it, it’s almost always a deer that set it off or a coon that pulled out. The coons that they do hold are usually caught high above the pad.