In my world nether, there is a floating lava pool and when I update a block around it on only the block it was next to was updated. I do not know how this occurred. (I had already tried to update some of the blocks)
Environment
(Windows 10) and Java version 9.01 (AMD Version)
That appears to be happening where nether ravines meet lava pools/lakes. The blocks are removed but the lava remains.