I'm not sure what's happening here yet, just putting this up in case it rings any bells.
I start with these tasks:

Use ctrl+Up to move the one selected task up a row.
This is the result.

The tasks are fine, it re-renders after moving around a bit. But the task isn't actually moved.
This happens on one tasklist, not on another. I'll save the .ini and .tdl and try to isolate the cause.
HTH
T