Taskbar Groups Spontaneously Rearranging Themselves

This just started happening a few minutes ago.  I updated to 7TT 5.5 a couple days ago. 

Without providing any stimulus to the task bar, all of a sudden my windows on the taskbar just rearranged themselves.  The order of all buttons within groups were preserved, but two groups just magically rearranged themselves to an order I've never set them to.  My mouse cursor was nowhere near the taskbar when this happened.

After I moved the groups back to the order they were in before, they rearranged themselves again seconds later to the way they were before I restored their original order the first time.

There must be other conditions involved here, because it's not doing it anymore.  It did it like three times in a row within seconds of each other.  After that, I force-closed 7TT from Task Manager and re-opened it.  After I re-opened it, the main 7TT window was acting weird.  It would disappear for a split-second and immediately reappear.  It did that a few times as well, spaced a couple seconds apart each time.

My taskbar is oriented vertically.  I'm using 10 Pro 1709.  This is the only program exhibiting strange behavior.  I don't really know how to quantify this any better at the moment.  Are there logs somewhere?  I can't find any in ...\Appdata\Roaming.