Well I'm not out of the woods yet, that was just a blank system with nothing else on it, obviously something is screwing things up on my end still.

I really doubt it, since the problem didn't show up on the test system using my theme, but at least I can start troubleshooting now. I think it's something configured with my version of Windows that it's tripping over. The frustrating part is I really can't think of anything else that changed besides moving to 22H2.

UPDATE:

I did more testing, it looks like Open-Shell is the culprit after all. From my testing:

Windows 20H2 + Open-Shell + Nexus = system tray expand icon works as it's supposed to
Windows 22H2 + Open-Shell + Nexus = glitch with the tray appearing into the upper left
Windows 22H2 + default start menu + Nexus = system tray expand button functions normally

I obviously can't blame Nexus for how it functions with a 3rd party program intervening also, so I'll have to figure out a replacement on my end. Sorry for the runaround.

Well, just took a good look at the code too. Not only is the tray expansion window repositioned, but it is also actively monitored from then on while open, and repositioned again if it moves to another location (if the popup animation of a panel has not finished, it is possible for Windows to move the panel back to its original location while the animation is still playing, and if that happens we move it back to where we want it).

So, the Winstep application is already "fighting" with Windows for the actual position of the panel. If Open Shell also wants to control the position of that window then it becomes an unfair fight, 2 vs 1 lol

There is also the possibility that something screws the calculation of the panel size (most likely due to a timing problem while popping up or so), which COULD make the Winstep application position the panel in the top left corner.