Since the last update to Rhino (6.11.18348.17061, 14.12.2018) flamingo nxt isn’t loading anymore.
Download the last of flamingo nXt .
Flamingo nXt 5
Solved - THX - File wasn’t available on the server when I looked for an update…
That means maybe the Rhino blocked by firewall and McNeelUpdate service not running.
That is not updated on download page.
Started Rhino today - problem occurred again - flamingo NXT will not load…
Restarted everything what I could reach - including my computer 
. Solved the problem…