Blend Space Input pin stuck to mouse (UE4.4)

Has anyone encountered this behaviour? I initially tried to adjust a 1D Blend Space, but when I released the mouse the input pin still follows the mouse and still gets stuck, even after reopening the project!! Very annoying and breaks the whole thing forever, even after I delete all the samples and attempt to start over…

I’m getting this too! Shame nobody else has replied and I realise how old this thread is. Have you found a fix?