when items are taken out of the ready use inventory and a crate is opened the items automatically re appear in the use boxes.
i have un eqipped the items (pic top left)
open and closed the crate (pic bottem left)
and all items are back in the inventory. (pic bottom right)
Thank you for your report. This issue was, however, submitted earlier as MCPE-16060. Please perform a search next time to make sure your bug hasn't already been reported.