FallingSand entity spawners causing graphical glitches

When FallingSand spawners spawn an entity, the block in which it spawned seems to disappear but only visually, because if, for example, it was a fire or lava block and a player in survival gets in contact with the invisble lava or fire block they take damage. The picture provided contains a FallingSand spawner modified to spawn lava. The lake is completely solid yet it appears as if pieces of it were missing.