@VictorLerp
I have tried the fullbody IK control rig in 4.26 and it works great. I attached controls to the left hand, right hand, left foot, right foot, head, and pelvis on the mannequin skeleton.
If I save the control rig and then close the project, when I open the project again the fullbody IK rig node is gone. All the get control transform nodes are all still there. If I go back into the control rig blueprint and re-add the fullbody ik, whether I re-add the connections or not and restart the project the fullbody ik node is gone.
Also, when I’m working in the control rig with the fullbody IK node, the node will often disappear even though all the location/rotation connections to the control transforms are still there.
I experienced this on my Windows 10 PC