Hi

I found a hard way of doing this.
We faced the exact same problem.
Our huge level used to run fine in WED with a -nx 255 value,but did not run as a standalone version.
To achieve this :-

1).Open up that level wmp using a text editor.
(I used Wordpad ).
2).Search for the word "level".
3).You must find something like

level 0 {
<space01.$$w>
<crapola.lmp>
200
0
60
<intro.WDL>

4).The first value which is 200 above is the nexus value.Change it to your needs.

5).Save this file in Wordpad.

6).Open WED and then compile the level.Then publish/resource your game.

Then it worked fine for us:)

CAUTION :- After Step 5 , do not open the File->Map Properties to check the nexus value because on exiting that window,the value of 200 will be restored.Even if u accidently checked this,not a big deal.Just open up WED again and then your level.

Let me know if this helps

Zazang.