Whenever I try to use the Child Of constraint, things go rather insane lately! If I turn the influence up to anything above 0.0, the object with the constraint flies off somewhere. But even weirder, if I set the constraint to 0.0, snap cursor to object, that works fine. But if I then set influence to 1.0 and let the object fly off, snapping the object back to the cursor just makes it jump to somewhere else. And every time I snap it to cursor, it just jumps to a new spot! What’s going on, and how can I make this stop!
Not sure, but it sounds like you have to “Apply” -> “All Transforms”, maybe give it a try.
I did, the resulting transforms are completely off, often similar or identical to the problems described, but just as often completely new wrong ways…
There is a button for applying reverse transformation in the constraint interface
I tried it. It didn’t seem to change anything.