While traveling the Nether, little lava blocks can be found that aren't flowing when they should be. Updating them with a block will cause them to start flowing.

To Reproduce

Create a world with the seed 1602560007. Go to the Nether and teleport to my coordinates. (Coordinates are in the screenshot.)

Note - This is for Bedrock Edition. I'm using a texture pack to make the game look more like Java Edition.