A Unity ID allows you to buy and/or subscribe to Unity products and services, shop in the Asset Store and participate in the Unity community.
Separate names with a comma.
Seeing the same issue, and looking at the Editor log: Registering precompiled user dll's ... Registered in 0.017142 seconds. Start importing...
Considering what a giant cash cow the Asset store is for Unity, it is strange that they are so unwilling to invest in it... :(