Just running a few more runs to see. Yep the preview folder was there but empty. Will let you know shortly on the bat file/errors.
Cleared output, ran a new run of 2 after launching from the bat file:
changed landscape
running generation thread
planned runs: 2
Map name: NitroGenMap1
creating output directory: NitroGenMap1 C:\Users\Dan\Downloads\NitroGen_WorldGenerator\output\NitroGenMap1
output directory created
... running terrain generation ...
exporting (1/3)
exporting (2/3)
exporting (3/3)
... terrain generation ... DONE ...
... running world mapping ...
java.lang.ArrayIndexOutOfBoundsException: 1024
at nitrogen.a.c.a(Unknown Source)
at nitrogen.a.c.b(Unknown Source)
at nitrogen.a.c.c(Unknown Source)
at nitrogen.a.c.a(Unknown Source)
at nitrogen.gui.NitroGenUI.run(Unknown Source)
at java.lang.Thread.run(Unknown Source)
1024
Total time taken: 1 min 57 sec
Map name: NitroGenMap2
creating output directory: NitroGenMap2 C:\Users\Dan\Downloads\NitroGen_WorldGenerator\output\NitroGenMap2
output directory created
... running terrain generation ...
exporting (1/3)
exporting (2/3)
exporting (3/3)
... terrain generation ... DONE ...
... running world mapping ...
java.lang.ArrayIndexOutOfBoundsException: 1024
at nitrogen.a.c.a(Unknown Source)
at nitrogen.a.c.a(Unknown Source)
at nitrogen.a.c.c(Unknown Source)
at nitrogen.a.c.a(Unknown Source)
at nitrogen.gui.NitroGenUI.run(Unknown Source)
at java.lang.Thread.run(Unknown Source)
1024
Total time taken: 0 min 57 sec