Location of Shipwrecks appears to be incorrect

[hpoom]

If you load seed 600000222763165 in both creative minecraft and in amidst. Fly to the location amidst reports as locations of Shipwrecks. There are no ships to be found.

You can find Shipwrecks in this seed, but none of them are at the locations reported by amidst.

Seed came from reddit but I can produce the same results with random seeds also. Ocean ruins and other ocean features appear to be reported as close to their real location, but shipwrecks are incorrect from all my testing.

[moulins]

It seems Shipwrecks locations moved from 1.13-pre6 to 1.13-pre7: if you use 1.13-pre6 or earlier, Shipwreck locations given by Amidst are accurate. I'll have to investigate to see what changed in the Minecraft code (and to check if Ocean Ruins are affected too).

[fwiffo]

Is this possibly related to MC-131462? It was reintroduced in pre7 but was fixed again in 18w30a. The timing seems suspicious.