Very well done indeed, Alvin. But I didn't see a UCS jump or an anomaly.
...Unless you're referring to the "Y" character jumping from one side of the Y-axis icon to the other. That's normal and means nothing; happens with the WCS icon, too. Go to World Plan view in any drawing at all, place the cursor near the bottom of the screen and "roll" it back and forth a little by holding the Shift key while dragging sideways with the mouse wheel depressed.
Yeah, working with it some more, and really, really keeping my mind open to all possibilities, and stopping when I see the "anomaly" occur to look for every other possibility that it could be that would indicate that TurboCAD is behaving correctly,
I am starting to again believe it is a VERY GOOD illusion/deception.
Even at the end of my video, when it is paused, I can see another possibility. One that would indicate that all is okay. That is the image below.
Then... this really made it clear to me that there is no "view shift", or "anomaly". I put that little "mat"-- the Group that is the black-outline polyline with the orange-brush and compass-directions-- on its own Layer. Once I thought I used the Examine Tool such that the "anomaly" or "view shift" occurred, I stopped. It looked like it was messed up-- convincingly as if the view shifted, the objects displayed as having moved, or something. But then I changed that mat's Layer Order to one that is higher than the other Layers that all the other objects are on. The fact that all was okay became plain and apparent as day.
(That's the second screen-capture below.)