stretch ik bug

i try ti use the stretch function in the ik constraint, but i got 2 troubles : first it scale the mesh, second with leg it dont work as i want. basically the knee dont bend because all the leg is scaling. i m a bit ennoyed because thats my first paid job and i dont want to go back to maya. but i m a Bit stuck here.
thanks for your help

So you have a bone with both the IK and the stretch to constraint applied to it ? … And from the sound of it you probably also have the same target object/bone for both constraints as well …

Well you shouldn’t have both constraints in one bone . The stretch to will like you said scale the mesh’s vertex group assigned to it as well as the bone itself which screws up whatever the IK solver is trying to calculate … in short just a mess .

You should think of the bones in an IK chain as though they were bones in our bodies . The IK solver simulates resistances in rigid jointed structures like real bones . Adding a constraint that scales the bone itself in that setup is like turning bone into jello .
And you should consider the stretch to constraint more like the fleshy muscles in which stretching/scaling is a very wanted aspect of it’s function .

If you need the functionalities of the stretch to bone you need to add a separate bone and apply the stretch to constraint just to that bone . The new bone should also be the child to the parent bone to the shin(? from your description ?) if it is to emulate a calf muscle . And also it would be a good idea to disconnect/off set the new bone if you want the effect to be noticeable . But both bones/constraints can share the same target object bone which might or might not be what you want .