Had one bow with multiple enchantments on it in my personal inventory and was going to enchant another bow as well. I didn't like the preview enchantment so I was going to enchant a book instead to clear the table. Canceled out of the Enchant UI and it dropped the bow I decided against enchanting. After I picked it up I realized my Bow with multiple enchantments was just a regular bow all of the sudden. This also happened with a pick axe.
MCPE-10765
Enchantment table wiped enchantments
Resolved
Duplicate
1
Confirm also on windows 10 I only seen this happen to leather helmets tho as I haven't been able to enchant bows to test this out.
One solution is to exit out the enchantment table so you throw the items so you get the enchants then put it in a chest and once your done enchanting get the stuff from the chest.