Multi Artist Tagging Problem

I've made two compilation folders of files from two different artists called IEM 1 & IEM2. I've tagged all of the files under Artist & Album IEM1 or IEM2 instead of the original names. The only place the original artist is shown is in the far left column under artist and even the track numbers correctly correspond to those in Filename.

The problems is that even though I've saved the correct order and placement, whenever I open the folder new, the same two from IEM 2 are in IEM 1 and the second artist MP isn't listed but when I add the MP directory, the tagging is correct as IEM 1.

So this is causing the MP files not to be added to WMP11 and to my MP3 player (Zune). I've saved and added numerous times but it won't change.

This has worked fine on other similar compilations I've done. What am I missing?

Any assistance is greatly appreciated. Thanks!