2001 S80 T6 No low beams again - car eats shunts?

[T64me]

I am trying to help a friend with a 2001 Volvo S80 T6. I replaced the low beam shunt for him about a year ago. He has the same problem again now where the low beams will not work for about 5 minutes - then they finally come on. This is the same problem it had when I replaced the shunt a year ago. Problem went away for a year but now it is back. I don't understand why this car would "eat shunts" but it seems like that is what it is doing. Any idea why it would do this?

Thanks in advance for constructive input.