I found this bug while playing Minecraft PE. When lava spreads into a new area and its level is high enough, it's not generating a new source block. When you try to scoop the new block with a bucket, it only picks up one of the source blocks that was originally placed. I tried this while trying to build a typical "lava generator" in which four source blocks of lava are placed around a center empty block. The lava spread should produce a lava block that is a source block itself, but nothing happens. The block even appears as a source block, but it cannot be scooped with a bucket. Is anyone else having this problem and if so, is there a way to fix it?