There is a bug at the platinum primary input for multi instruments, currently this causes spikes or random silence.
I have reported this bug and hope there is a fix.
In the mean time I have a workaround that I am more than willing to share.
Try and Use 1 x multi per instance of kontakt5
1st kontakt5 instance 1st string multi
2nd kontakt5 instance 2nd string multi
This will also benefit you with more controlled freezing and mute/solo , exclusively per instance.
I hope this helps you.
I thought I might add that the workaround solves the spikes not the random silence, I have experienced the random silence with Ableton rewired and have not had time to look for a workaround. This is also a multi and I believe this bug is affecting people differently at the same location. So Give the kontakt5 single multi workaround a try and see if it helps you.