In my recent rigging tests i encountered some weird behavior when using animation constraints.
In this example you can see the foot is lagging some frames behind. Also if you cancel the animation, the bones are not snapping back to its initial position. This "bug" triggers (i believe) randomly. but you can force it by switching to the "iTaSC" IK solver and switching from animation to simulation and then back to the normal ik solver. if the "bug" is still not there, redo the procedure.
In this example the bones are switching to a wrong location when canceling the translation (G) by hitting the right mouse button.
I know that currently most of the constraints (like the "track to" constraint) are calculated after the IK constraint, so that using it can cause some glitches in the viewport. but i believe this is something more complex than that. Is this a bug and should i write an offical bug report, or is it a known issue?