I use the seek bar in some of my apps running on Transformer TF-101 ICS 4.0.3 and the seek bar shows and works fine. I am only using version 1.9 B4A. What version are you using?
If you still have a previous version like 1.9 or below, you might try them. I know there is a change as to how 1.92 and 1.9 handles some issues in ICS.