Sorry man i can't help you with that but if you have the world seed you can try to go on MC edit and copy your builds to that new world with the same exact seed.
Or maybe it's just because you logged in a more recent version and there are new biomes being added
That's all i could think of.
Also make a copy of your bugged world just in case something happens.
I hope this helps you!
-sonicplasma
