Unable to establish all IK bone chains!

Unable to establish all IK bone chains! IK features, in Live Action Advanced projects, may not be applied for some limbs.

As these features are optional this message can be ignored if the missing IK bone chains correspond to the missing bones. If the bones for a limb exist this message should be considered as it may be an easy fix to enable the IK functionality on those limbs. Visit the IK bones & IK features page for more information.

Blender

Missing IK bone chains will be highlighted in the add-on to bring attention to which limbs might not be fully compatible with the IK features of the platform.

Maya

>>> [WARNING] IK joints chain check - FAIL.
  > Left Arm joint chain IK compatible - True
  > Right Arm joint chain IK compatible - True
  > Left Leg joint chain IK compatible - True
  > Right Leg joint chain IK compatible - False
  > Unable to establish some or all IK bone chains.
  > IK features, in Live Action Advanced projects, may not be applied for some limbs.

In this example case, the Right Leg does not have the Foot in the Up Leg hierarchy, hence the IK chain is not possible.