When using a new super flat world in any preset with structures enabled both within the parameters of the preset and generate structures set to on you can not use the /locate command and it comes up with "could not find that structure nearby" even when you are right near a structure e.g a village. along with this issue is that ender eyes cannot be used on super flat worlds with strongholds generated in them to locate the strongholds.
This effects all preset super flat worlds that have village or stronghold ect in the preset.
Both already reported, duplicate of MC-131749 and MC-129433.