Toby Reed

ive now fixed it, i had to meddle with the "DIM" world files as spigot now seems to read from the vanilla files rather then the old file location used for spigot.

yes i use spigot with some plugins, none of which i would've thought delete the dimension, should i try uninstalling them?

the same thing is happening to me on my server. The seed is exactly the same, but i dont have any manmade structures in the nether, like i had before(in 1.14.4). Strangely enough though, if i replace the current nether with the backup of the nether, its still exactly the same, including changes i made in 1.15.1. Can there be any further assistance with this, as i reckon its the update itself that reset the nether.