Testing out combat on Hard difficulty on 15w38a, died to enderman, respawned went around building and all monsters that were hostile towards me were invisible including the enderman and kept hitting me. All monsters that were not aggressive however were still visible.
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Thank you for your report.
However, your ticket has been resolved as a duplicate.
This issue has been linked to the original bugreport: MC-68403. You can find or add further information on that report.
Please search before reporting any bugs, as it's likely that one exists already.