Dopus not stacking windows

For some reason when I have dopus pinned it opens what looks like a new window for some reason. Anyone know why this is? When I click it once the pinned program doesn't just open it opens another one and leaves the pinned one closed.

Before it's opened:

After I Open it:

It's a flaw in the Windows taskbar.

Un-pin Opus, then re-pin it and it will work normally again.