Here goes, shot a black bear at about 25 yards with a .458 Win. Mag, using factory REM. 510 grn soft points. Aimed right on the front shoulder, at the shot the bear dropped in a cloud of dust like hit with a sledgehammer, then managed to get up and disappear in the bush never to be seen again or recovered. Sparse blood trail that didn’t go very far and dried up quickly. Next day we thoroughly circled and combed the area again, no sign of iron bear.
You either missed (as in, not hitting anything vital, as suspected) or failed incredibly at tracking. I have seen dozens of bears hit with various .45 cal centerfire rifles with many different bullets... none of them were lost, all went down quickly, there was always lots of blood and there was always little meat damage... as in, a thorough and effective wound channel without much ancillary bloodshot, and there was always a pass-through... apparently your mileage varied.