There now appears to be an issue now that only affects enchanted items that contain mending. The mending function works so so I guess but the item gets stuck while using and doesn't collect all xp orbs; for example; the pickaxe jumps and gets stuck in lower area and doesn't function. The fishing rod does the same but if you switch hotbar items momentarily the item returns to functionality.
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This happens to my Mending Enchanted tools as well on Windows 10, it's annoying enough that I'm not playing until it gets fixed, also playing on a realm, haven't tested on local world yet
Confirm here too. Latest version - 1.2.13 on both Xbox One and Windows 10 (there is a duplicate bug report MCPE-32550 related to Win10).
It appears mending is still working, though possibly at a reduced rate. I can tell it's working--eventually--on a fishing rod, but not on a pickaxe.
Thank you for your report!
However, this issue has been closed as a Duplicate of MCPE-31326.
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Can confirm seeing the same behavior, appears to happen when there is a lot of ex at the same time. Can reproduce via a mob spawner farm. Kill a number of the mobs then watch as the tool appears to freak out. I am on a realm.