I've noticed this before, but thought I'd simply not been paying attention, but quite often my progress isn't saved with achieve's.
With both books and random dungeons, the fact that I've done them doesn't always stay. It'll check it off, saying I've explored/read it, and then next time it'll be missing.
This is rather annoying, as I've been farm-exploring and now one of the places I had spent hours on searching for is no longer checked off.

Another bug I've found is with the stash. I was working on my second page, which is supposed to cost 100K for each 14 slots. Instead, it was 10K, as the first page had been. Since the third page is still 200K each, I know this isn't a price change, but a bug.
I'm not sure if it was because I went onto a low leveled character and it messed up (I've been playing a level 35, and switched to a level 12), but it doesn't seem to be acting up again for the last page.

Edit: Added on second bug.
Edited by AniBlade#1648 on 6/2/2012 2:47 PM PDT