When player inventory and hand is full items on the ground will still be collected, but not added to inventory. The item will be lost from the game as it is not in inventory or on the ground. This is a new bug in 0.13.2 and did not happen in 0.13.1 of Windows 10 beta version.
Linked issues
Comments

Take a look at the comments on MCPE-9960 to see different ways that you can potentially recover your "invisible" items.

For what it's worth, it ends up this was a different bug, but it's now being addressed in MCPE-9960 since we mixed the two together back in February.
Duplicate of MCPE-9960
(Also, this has been around for a while before 0.13.2 and is reported as fixed in 0.14.0)