/locate ruins, shipwrecks, buried treasure coordinates result in no structure at location

The updated /locate command that now includes underwater ruins and shipwrecks returns coordinates where no such structures are located. Same with buried treasure.

Examples from pre-1.4.0.5 generated world, Seed -670219719

Shipwreck -600 y? 200 (structure not found)

Ruins -744 y? 248 (structure not found)

Buried Treasure -696 y? 136 (no treasure found)

NOTE: When same seed used to generate new world, the local area contained sea grass and ruin blocks and treasure, which was not generated in the pre-1.4.0.5 world.

I suspect the chunks had been previously rendered, but the /locate command was still referencing the invalid coordinates for nearest structures.

Please advise if issue with generation or bug with the /locate command.