eyefinity disables aero thumbnail preview

I've recently built my new pc with a Sapphire R9 390 before that i had the HD7750.

With the HD7750 i had a 2 monitor setup (eyefinity) and the taskbar going across 2 screens, when i hover over the taskbar i got a little thumbnail telling me what was in the window.

When i built my new pc, i still had 2 monitors and it done the same, hover over the icon in the taskbar and the thumbnail preview showed me what was in that window.

I then got my 3rd monitor, re-setup eyefinity and noticed that the taskbar preview disappears!

But whats strange is, if i move the taskbar to the left or the right of the screen, it comes back, if i move it to the top, it disables again, so it seems when the taskbar is long it stops working.

Aero is enabled, and taskbar effects is turned on.

What would fix this so i can get the taskbar thumbnail previews back when the taskbar is on the bottom?

This problem is with windows 8, but no one is answering on 8 forums haha!

This is what i mean by aero peek (i know this screenshot is from a win 7 machine, but same thing on win 8! as im not on my machine atm!)



My PC specs:
CPU: AMD FX8350 Black Edition
GPU: Sapphire R9 390 NITRO
MOBO: MSI 970 Gaming
Screen Setup: 3x 21.5" LG monitors
HDD1: Kingston 128gb SSD
HDD2: WP 1TB
HDD3: Seagate 2TB
Case: NZXT Phantom Full Tower (Orange/Black)

Thumbnails get disabled with Nvidia surround too. It is a "feature" MS never cared to address. I use a vertical taskbar.