Long press (bulk item) inventory manipulation is all but impossible on the latest version (0.16.0) of Minecraft PE.

UI elements that have no need to be scrollabable due to space issues are scrollable and it is rather hard to keep a needlessly scrollable inventory panel perfectly stationary while holding one's finger down on an inventory slot for a period of time. The scrollable inventory space moves and as a result the transfer of items is aborted.

This isn't really demonstrable in a screen shot and also affects the Nexus 7 2013 tablet. Easy to reproduce, open a chest with inventory items and attempt to transfer a stack of items by holding down a finger on an inventory slot (as distinct from pressing a space 64 times).