Question with “one or more interfaces“

[Catchher]

When i set joy parameter interfaces="I1, I2", and only network data from I1 can be capture and analysised.
I have tried many formats of this parameter string, such as "I1I2", "I2I1","I1;I2","I1 12". it dosen't work for me.
conclusion：interfaces="I1(with an arbitrary string)" equals interfaces="I1"