Mmmmh... I don't think that plugin cuase that. It seems to be a nodes constraints issue, besides, I can see a lot of missing stuff in your scene's snapshoot. let's try this first:
*In the launcher, select "Activate Console", it is just below the "Play game in fullscreen" option.
*In studio, load the scene. Once loaded, press Ctrl+I to spawn the Node constraint's display, If any, uncheck all, every single one ofthe nodes by clicking in the rightmost checkbox inside the Nodes Constrains window.
*The issue must fix (or at least, the actors will stop contorting). next, enable constraints one by one until you see your actors twist writhe again, there you will need to adjust the constraint point to fix the scene.
*If nothing works even though disabling nodes constraints, go to console window and make a screeshot and share it here to see whats going on.
*Or bette yet, share that scene file here in zip/rar/7z format to take a closer look.