Whenever you start mining a block in survival, switch over to adventure, and try to mine the block again, it appears like you're mining it (only client-sided). When you try to mine any other block in the world or use a different slot in your hotbar, it does not work and behaves like adventure mode should. Works on singleplayer and multiplayer.
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We're tracking this issue in MC-19676, so this ticket is being resolved and linked as a duplicate.
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