Just replicating my ZPM settings from my old SP3 environment to new 2017 U2 and found what looks like a UI bug:

  • go to Configuration > Subscription Service Content Download
  • change "Select vendors to use in the system" from All to Selected
  • after changing to Select the vendor list does NOT appear

In SP3 when changing from All to Selected the list of vendors went from greyed out to selectable so we can untick vendors we don't use. Seems like this setting now doesn't activate properly in 2017 U2?