This bug report applies to the spigot.yml feature to merge like-items. This feature works as intended, but in this described instance, can cause the "disappearance" of blocks.

Reason:
MCMMO's (by @drtshock ) double drop mining feature making ores drop 2 instead of 1 block/item. I'm sure any resource that causes multiple drops of a single item will cause this issue and is a result caused directly by the mechanics that merge the items.

Bug:
When a player gets a double drop of an ore mined on the ceiling (with solid blocks above it), the ores combine and are forced upwards. When there is no room for the ore to go up, the dropped items seemingly find the closest open space traveling upward. If there are no caves or open cavities between the ores and the world surface, the blocks magically appear on the surface. This has been proved and tested multiple times and is only fixed by disabling the merge-items feature.

My request is that the merge-item feature be slightly modified so items merging don't take a trajectory when they combine.