When you are holding a shield and a trident, both of them are invisible. And no, the hide hand option isn't enabled at all and there is no texture packs or add-ons applied. This is visible by going to 3rd person front or back, this also affects players and mobs.
Edit: Also in the paper doll or in the inventory, the trident and shield appears
Thank you for your report!
We're actually already tracking this issue at MCPE-44647, so we will resolve and link this ticket as a duplicate.
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