I can pin Firefox Portable to the taskbar, no problem. If I click on it from the taskbar to open it, it opens up exactly where it is pinned at.
But when I pin OBS Portable to the taskbar, it won't open up where it is pinned. It will open up and appear after every other program that is pinned to the taskbar.
Just to be sure, I unpinned both Firefox Portable and OBS Portable. And then I used PortableApps.com Platform to pin both programs. Firefox Portable worked. OBS Portable did not.