I don't know the process of how this happened, but my friends and I were playing survival when one of them couldn't sleep because of nearby mobs. We went into spectator mode and confirmed that no mobs were around or underneath the house, and when we changed the difficulty to peaceful mode, she was still given the same message, despite the presence of monsters during peaceful is impossible.
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However, we are already tracking this issue, and this report is a Duplicate of MC-143895, which is a report that has not been resolved yet.
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