You can always turn off whatever feature is blocking you from saving your worlds. Like if you have it clear cookies when you close your browser or something. I hope you find the culprit!
Great game.Though, I feel like maybe a few things are missing. (Examples: the abandoned mineshafts being underground, villages and npcs, and texture pack compatibility, and less glitchy squids) But overall, BEST MINECRAFT FANGAME EVER!
You can always turn off whatever feature is blocking you from saving your worlds. Like if you have it clear cookies when you close your browser or something. I hope you find the culprit!