New answers tagged assembly-references
Click on assembly and press F4 to load its properties in Visual Studio. Try changing the value of Copy Local to true. And check if your project uses the latest .NET version.
As requested in the comments on my original quesion, here is a screenshot of the assembly reference in the references folder. I can only find one version of this assembly so I don't think its a version mismatch.
If I remember correctly you also need to add a reference to Microsoft.SharePoint.Client.Runtime.dll. That is a separate assembly, that needs to be referenced on top of the Microsoft.SharePoint.Client.dll
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