This is an old thread but since there must still be some people here looking for answers, there is a workaround for this.
I’m guessing the problem lies with Actor references or something along those lines. The first answer from this thread was partly correct. When trying to clear a reference, you should set the variable without an input. This does clear the variable. But not entirely. There are still some traces left, for example the coordinates get reset to 0, 0,0.
To counter this, make a branch, type “==” and get the Equal(Object). Leave the select asset clear and the branch should be able to tell if the variable is in fact empty or not.
Good luck guys, this worked for me, hopefully for you guys too!