Bukkit

What steps will reproduce the problem?
1. Set Worldborder to X
2. Trim World
3. Fill World with 512 block outside the border (it doesnt matter how many block after the border, it happens everytime the world gets expanded)

What is the expected output? What do you see instead?
World should be filled completely but instead the the first chunk after the old world ended has a lack of trees,grass,snow etc.

What version of the product are you using?

The newest on Bukkit, 1.8.5

Do you have an error log of what happened?

Nope, everything is normal.

Please provide any additional information below.

Ive tryed it several times but everytime it happens the same thing, if im generating the chunk by visiting it , it generates like normal with grass snow etc.
Ive restarted the server before and after every trim and fill process.
There is no error in the console or something else
[02:11:46] [Server thread/INFO]: [WorldBorder] [Fill] 97 more chunks processed (262989 total, ~99.0%) (free mem: 5494 MB)
[02:11:48] [Server thread/INFO]: [WorldBorder] [Fill] 3784 more chunks processed (266773 total, ~100.0%) (free mem: 5632 MB)
[02:11:48] [Server thread/INFO]: [WorldBorder] [Fill] task successfully completed for world "world"! (free mem: 5606 MB)
This is the log, now error before and after this part of it, only savings but nothing else.
My english isnt the best but i hope you can understand my problem^^

I'm getting a ton of issues with it. Lighting problems, half generated structures. It's essentially unusable currently.

not experienced any of this, just saying
but I have a 12c/24t processor with 32 gb ram for 1 mc server