Villagers won't change their textures and just look the same even if they have different jobs. However, they will change textures depending on their biome, but not for their job. No matter what, they will not change from their current texture (which I assume is their default/jobless texture) This issue persists between worlds as well.
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We're tracking this issue in MCPE-160475, so this ticket is being resolved and linked as a duplicate.
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