More complex summery

When a command block is filling an area with snow layers, any of those snow layers that are "Melt-able" (close enough to a heat source) will be affected - they will keep flashing once mined. Also, they will stop flashing and just disappear when a block is placed there at the right time.

How to reproduce

1. Place a repeating command block filling a small area with snow.

2. Place a heat source (campfire is ideal) two blocks away from the edge. This should only make one block "Melt-able"

3. Mine a "Non-melt-able" snow layer which is being filled. Notice it just reappears instantly.

4. Now mine a "Melt-able" snow layer.

Expected result: The snow layer reappear instantly just like the other "Non-melt-able" one.

Actual result: The snow layer keeps flashing.

How to reproduce second part

5. Place a snow layer in the flashing one. There are three outcomes:

A. The snow layer keeps flashing. In this case just try again.

B. The snow layer returns to normal. In this case, just mine it and try again (temporary work-around). 

C. The snow layer almost stops flashing completely and only flickers occasionally. This is really weird as there is a command block trying to fill it constantly.

More reliable temporary work-around

**Just place a block in-between the snow and campfire, making it "Non-melt-able" and then remove it. This will reset the snow-layer until it melts.

Note: Melting is another way of reproducing this bug rather than mining the snow layer. However, it is slower and therefore hasn't been included in the how to reproduce section.

Final note

**This should not happen as "Melt-able" and "Non-melt-able" snow layers should act the same (apart from the fact that the "Melt-able" one melts). Also, I have attached a testing world in the hopes someone can provide a video of this bug (my recording software is not functioning correctly).