I suspect that you simply did not get a vital shot on the bear. The fact that you had blood on 2 sides of the trail shows you had a pass thru shot. You simply may have hit him above or below the vitals.
Bear are tuff animals if you don't get a vital shot. If you hit lungs or heart, that bear is dead. If not, your likly in for a long wait before he expires.
I tracked a bear recently that was gut-shot with a 180 grain from a 308win. We found interanls organs of all kinds including his entire intestinal track laid out like a striaght rope along his trail. Not much blood at all, we mostly tracked pieces of internal organs and trail signs such as over turned leaves.. That 308 gut shot opened him up like a can opener and his insides were coming out in pieces.
We tracked this bear for at least 6 hours that night till 1:00am. The next morning we resumed the tracking with 8 guys and finally found him dead in a creek nearly 2 1/2 miles from were he was shot.
The tracking process was like connecting the dots. A piece of organ , then a over turned leaf, then a spot of blood, some distrubed dirt, a piece of organ , ect, ect.
If there is a vital shot and a pass thru, a good blood trail will develop very quickly if not at the point of the original hit. If this did not happen, you simply did not hit vital and I don't care what gun your shooting, tha bear is gonna be tuff to find.
WHat gun were you using ?