I rarely use lure for beaver. I mostly use blind sets, swim throughs. Main reason is a trap under water gives you the three day trap check window. Even before cages I rarely used lure and depended on blind sets mostly.
That being said, back before I had conibears and a lot of people used exclusively scent sets for beaver I never noticed much fear of lure even though it was overused during those times.
What can scare beaver though is going into an area and stomping all over it. You are looking for that perfect spot and all that activity can scare the beaver into holding up in their den for an extended time or even cause them to leave the area.
I do think beaver can be reluctant to enter a lured cage because of the cage more so then the lure. That is my last chose for a set but sometimes that is all you can do. Give it some time.