sometimes if i merge the item gone, i don"t know where is goes

this game eats up some of the items when I merge....they just disappear!

when i combine items and suddenly i experience a bug then my item disappear.

when i try to merge the items, suddenly the item disappear and i cant seem to make it appear again...

When merging instead of actually merging two of the things of a kind both disappear

the items appear and when I put them to merge it's as if they weren't there

The items gets disappearing while merging for many times

I drag 5 lv3 corns together to create 2 final corns, but it keep flashing (the animation before they merge together), when i seperate, there're only 4 left, then I can only merge 1 final corn plus ...