It appears there will be no 128 export in V18 due to some logical legitimate reason.
Not sure what solutions are out there. Lots of work arounds none of them easy.
http://cloud.netfabb.com/
Is great for fixing the problems with the STL files that AM spits out. Unfortunately it does not work for me when I upload stl that have been exported higher than 64.
And 64 is way to low of a resolution for most prints.
You could model in more splines as a work around but that is a headache and not really practical.
You could download the free netfabb basic software and give that a go but I have not had success with it in terms of fixing 256 exported stl files.
To be fair many programs spit out stl files with problems, its kind of a known issue.