Well, did you ever enable the hand histories to be saved? when i first started at ACR, I had noticed that the hand histories weren't appearing. after going into options , located bottom of history window, noticed the save histories check box, in the upper left I believe, was unchecked. So if your not getting any hand history, that be the case. also might want to change the number of days the files are held before they are replaced by newer ones.
As far as the mucked hands, sites do this in order to prevent players from using the info to figure out their shuffle program. It also prevents players from being able to determine how you would play certain specific hands, and thus develop a specific counter strategy to those plays.