Hello, the problem or bug of the generation of structures, when you travel to a land that is not yet generated and where a stronghold should be generated, is not generated, but if you recreate the world and travel back to the same coordinates, if this is generated .

To know that there is a stronghold in these coordinates use a third party program because the ender eyes only indicate one that I have already generated and activated.

Even the /locate command only shows the stronghold it already generates.

The world was created in version 1.11.2 with the option that YES structures are generated and updated to version 1.12.

The only mods what I used is Optifine and BetterFPS but I think the mods doesn't cause the problem

In the image MCEdit Map.PNG it is clear how those chunks are not yet generated, the white square shows the location of where the stronghold should be generated.

If you want more information, tell me and I will provide it to you.