Chests empty after upgrade

We upgraded to 14w26a, but we had a lot of blocks that were transparent. We downgraded to 14w25b which resulted in a lot of missing blocks (not transparent - they weren't in the world anymore). Once I saw that Dinnerbone fixed the bug, I used 14w26b. All blocks were back, and everything seemed fine, but all chests (exept for ender chests) were empty.