Don't exactly understand why your getting this problem. I started up the old hammer and made a little test map. Compiled it with the latest Zoner's tools with only -nowadtextures. It worked fine for me, the player model stayed there, was lit fine, and all the guns I dropped stayed as well.
I simply made a func_illusionary with a null brush directly on it. For the func_illusionary I used these settings:
Render Mode: Solid
Amount: 255
I then made the same size brush and assigned the null texture to it. I have one light_environment and an info_player start.
.map is here if you want to compile it yourself: http://s90567463.onlinehome.us/test.zip
Hope this helped.