Hostile mobs create inside interiors despite high lighting levels. They did not create in these interiors v 1.14.60 and previous versions (due to high lighting levels).
Comments 2
Cleaning up old tickets: This ticket had been set to 'Awaiting Response', but has not received a response from the reporter (~3 months+) so is being closed as Incomplete. If you feel this is still a valid issue then please comment, or create a new ticket following the Issue Guidelines which includes steps to reproduce the problem.
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Can you provide a picture of the interior?