Testing IK solvers, I create a leg armature chain composed of Leg.R, Shin.R and Foot.R. In the heel (edit mode), I add a separate bone, not parented to anything - IK_Leg.R
In pose mode, I select Foot.R, then add an IK_solver constraint to it. As soon as I type in ‘Armature’, the leg collapses in on itself. This collapse is still apparent in object mode but the leg looks fine in edit mode. If I remove the constraint or decrease the IK solver influence to 0, the leg regains its natural form.
The manual (manual/user/htmlI/x7174.html) makes mention of something like this when teaching how to add an IK_solver to a wrist:
“Choose “Hand.R” and add an IK solver constraint to it in the Constraints Panel. In the OB field type the object name: “Armature”. The bone went to the centre of the armature, but we’ll fix this now. In the new BO field, that appeared in the constraint window, type the bone name “IK_arm.R”.”
But the “we’ll fix this now” doesn’t seem to occur.