Dropped items don't seem to interact with slabs correctly in the most recent 1.2 beta (I don't know if this is an issue under older betas).
The first problem I noticed is that items no longer go under slabs (see screenshot). The items used to slide under the slab and come out the other side, now they just pile up against the slab.
Another manifestation of what looks like the same problem is that now when an item drops on a bottom slab it will try to slide off instead if staying in place where it lands. Items in general seem to be repelled from slabs now.
Linked issues
is duplicated by 5
MCPE-25318
dropped items cannot travel under upside down half slabs
Resolved
MCPE-25592
Items don't pass through slabs
Resolved
MCPE-26296
Items won't flow under a top slab
Resolved
MCPE-27092
Entities do not slide under top-half slabs
Resolved
MCPE-29127
Items can not slide under upper half slabs in ice streams
Resolved
Attachments
Comments 6
Similarly, cannot throw a potion through a half slab opening, and when it hits next to that block, the splash affect doesn't pass through the half-block opening.
For any whom are looking for a more expensive fix....you can use trap doors, items will flow under it just fine.
Confirmed for 1.2.0.22