I've noticed multiple issues with my second monitor's taskbar.
I am running Windows 10 Enterprise x64 and using Classic Shell 4.2.4.

The "Show Hidden Icons" link doesn't recognize the mouse hovering over it.
The Start Button changes graphics when the mouse hovers over it, but it doesn't display to tooltip.
The Start Button icon is located lower than it should be. When I "Enable the Windows Taskbar on all monitors" the Windows Icon shows about 4 pixels above Display Fusion's Icon.
Right clicking the Start Button doesn't display a context menu. It should be Classic Start Menu's context menu.

I have only been using Display Fusion for 2 days so I don't have any more details yet.

EDIT:
Secondary taskbar will not "Auto Hide". (This seems to be a problem with Windows. Enabling the search icon on the taskbar makes it work correctly).
Clicking on the secondary taskbar's "Show Hidden Icons" button brings up the main monitor's hidden taskbar.

After a few hours of runtime, my pinned programs would disappear from the taskbar when the programs were closed. The placeholder was left but no icon or link. (I suspect this was due to upgrading to 7.3b4 without a restart, I suggest forcing a reboot.)

I experienced these issues with both 7.2 and 7.3b4.

Also, since I uninstalled Display Fusion, my primary Taskbar will not autohide at all but the secondary is fine.