One of my friend meet this bug
I forget his Device,maybe XIAOMI or HUAWEI
He enchant something and change the gamemode ,then the effort has disappear .He also founded that exit the game and enter it again,but it disappear once again.
And the experience will also reset.
This is the problem describe in Chinese :
MCPE版本:0.12.1.b7
bug名称:附魔效果消失
bug详情:当有时退出一两下或者切换模式后附魔效果消失
不光是附魔效果，经验值也会清零