Try d2checklist.com, like loudenkl suggested. It tells you what each of your guardians has. T was really helpful for me.

So...what I ended up doing in logging out and back in with another Guardian. Then switched to my main and voila, the icons for the 5 missing chests where now showing on the map...went to the locations and they were magically there. Must have been a glitch of some sort, but I new have all 68. Thanks!