It looks like some items are being lost when the Void Shulker is used. 

I am moving bases, so I bought 4 Void Shulkers last night (3/4).  I had a FULL chest of Sand, which I broke, and then used the Void Shulkers to vaccum up the items.  I noticed when I opened the shulkers that neither of them was completely full and no items were left on the ground.

I repeated this with a new FULL Chest of Sand, and the same thing happened.

I don't want the sand back, but I am concerned about this happening with other, more valuable items.

Happened on Evergreen.