HMC1118 Switch Power Up sequence

In HMC1118 datasheet is stated that "powering the digital controls inputs before the VDD supply can inadvertently forward bias and damage the internal ESD protection structures".

We have suffered several dies of this component by unknown circumsntances, but when read this note in the datasheet we have tried to reproduce the fail under these conditions but have not been able to reproduce it. How likely to suffer this problem is?

In case of producing this failure, is any symptom? low impedance in VDD,VGG??

Thanks and best regards,

Alberto