Hi,
I'm facing the same thing here, I have upgraded from 1.5.6.1 to 1.6 this weekend.
I tried to move the ads from the top hook to home hook, and I was able to see the ads on the home page.
When I moved them back to the top hook it was gone again, I'm trying to figure out the problem.
I had a check against the Prestashop demo, and it looks like I'm missing the "displayTopColumn" when I look in:
Backend > modules > positions
I guess this is why it don't get the two small ads beside the banner rotator going.
Anyone with some ideas here?
Thanks
Bjorn