Good day!
I have Houdini 9,5 apprentice HD.
I got problem while studying muscle system. For example I created an arm with simple geometry, 3 jonts and 3 muscles (biceps, triceps, and forearm). I selected two joins and used icon from shelf(point muscles) and created Two point muscles node. I got 3 muscles anchors. The problem is in Musle_anchor_middle - after joints rotate more then 90 degrees anchor reverses its direction. I though “look at” could solve this issue. But as muscle and anchor are made by script(or digital asset) all transform attributes for anchor are locked. I saw tutorial where this problem was solved by parenting muscle_anchor_end to null but when I try to make the same in my muscles I get permition error. May be I was wrong from the start, as long as I used script to create muscles, but it will be real pain to setup all character muscles manually.
Therefore i look for solution of this problem. I can upload scene if needed.
Thank you!

Yes please upload the scene.

here it is.
if I rotate chain_bone2 more then -68 degrees by Y-axis I get this problem
thanks!