Could you try and take 2 of the 3 drives out of your setup.
If it was me I would at this stage go back to a blank program
and just set up one drive and nothing else.
Yes, I was thinking the same thing. Tried it, still the same problem. I've jumpered the enable so it is on all the time, along with the positive and negative overtravel inputs, the safe torque off is jumpered out, and still no luck.
What revision RSL5K (Studio 5K) are you running?
Maybe the Kinetix 350 drive's modules communication profiles did not install corectly.
I would try reinstalling RSL5K (Studio 5K) making sure all hardware options are "ticked" when the install options are being prompted; I would also suggest the upgrade to the latest available minor revision if you have a TechConnect contract. https://download.rockwellautomation.com/webupdates/enter.aspx
Not really sure what it was. Something with the ethernet comm cables. Played around with them, moved them in the switch, and after a power cycle the drives came to life. One of those A-B things, where the stars have to align just right in order for it to work.