I've tried searching on this issue (and I've come across many issues with people not being able to add NuGet packages), but have come across nothing that can solve my problem.
I'm using Xamarin Studio for Mac and I'm trying to add the SQLite package to my Xamarin Forms project. However, when I click to add a NuGet package (either by right-clicking on the project or from the Project tab at the top), nothing happens. No delay or anything — I click it, no lag, and I continue doing whatever else I want. Has anyone encountered this issue before? I've already tried quitting out of the app multiple times and this has not solved the problem. Thanks for any help you can provide.
In case you are still searching for an answer: I've had the same strange problem. This is a bug in Xamarin Studio 6.0.X (In some installation, probably depending on system configuration or something like that) After updating to Xamarin Studio 6.1.X (alpha channel), it was working again ... If I find the link where I've found this answer, I will post it later!
来源：https://stackoverflow.com/questions/38513091/add-nuget-packages-on-xamarin-studio-for-mac-not-working