Hi German,
I think I am in the a similar situation than you one year later. My app runs OK if I keep the /lib/ folder with all the jars in the WAR project. I tried changing the assembly like you and now I have another error. I was wondering how did you handle the assembly for the EAR project. Did you change it as well?
Did you use maven from the console or always with the plugin?
Thanks, Leandro