Seed is 1173302408,
Originally started a survival world a few (pre) versions ago, used Eyes of Ender to locate stronghold in Pre6, was unable to locate a spawned end portal room, searched again in Pre 7 and Eyes of Ender instead lead to an invalid location. Recreated the world twice (in pre7) and in both instances /locate could never locate a Stronghold, and the eyes of Ender would lead to different locations that did not seem to contain a stronghold at all.
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Will close this for now; please reply if you can reproduce this in a fresh world, or a world upgraded directly from a release version (such as 1.12) to 1.13 pre-7.
Unable to confirm in pre7; creating a new world at 1173302408 and running
/locate Stronghold
gave a valid stronghold at 1192 ~ -1096, and eyes of ender also pointed to that stronghold. MC-124915 seems to be a different issue since that describes Eyes of Ender being able to be used in the Nether and End (where they point to (0,0)).