Basiclly, if you go to Survival mode and hit any block , and then switch to Adventure mode, you'll be able to hit the block and it will change it state (and appear is if you manage to break it), however, when it reaches it's last "broken" state in which one more hit and it should be broken, it just gets back to it's default state as if it was never hit, and you can just keep hitting that block, this only applies to the last block you hit in Survival mode.