Comment 4 for bug 1999342

I have the same problem, only with dual screen panels. The 2nd screen panel is ignored by compiz.
I can confirm other Window Managers do not have this problem.

Here are my outputs: (left & right panels)
_GNOME_WM_STRUT_AREA(CARDINAL) = 0, 1053, 1920, 27
_NET_WM_STRUT_PARTIAL(CARDINAL) = 0, 0, 0, 27, 0, 0, 0, 0, 0, 0, 0, 1919
_NET_WM_STRUT(CARDINAL) = 0, 0, 0, 27

_GNOME_WM_STRUT_AREA(CARDINAL) = 1920, 1053, 1920, 27
_NET_WM_STRUT_PARTIAL(CARDINAL) = 0, 0, 0, 27, 0, 0, 0, 0, 0, 0, 1920, 3839
_NET_WM_STRUT(CARDINAL) = 0, 0, 0, 27

I found a workaround:
When disabling "Expand" in Panel Properties, Compiz can "see" the panel.

After doing this, the output of ´xprop | grep STRUT´ changes to:
_GNOME_WM_STRUT_AREA(CARDINAL) = 2449, 1053, 861, 27
_NET_WM_STRUT_PARTIAL(CARDINAL) = 0, 0, 0, 27, 0, 0, 0, 0, 0, 0, 2449, 3309
_NET_WM_STRUT(CARDINAL) = 0, 0, 0, 27