Wrong assembly version gets loaded after a nuget package upd

For startes, all my development is done in the following version:

 

 - Windows 10x64 Enterprise

 - Visual Studio 2015 Enterprise Update 2

 - .NET 4.6

  - Azure SDK 2.9

 

Earlier today I decided to update an application to the latest versions of the components it uses. AS part of this effort I updated Systems.Collection.Immutable to version 1.1.37.

 

After the update of this package my unit tests fails and the application wont start up again because it complains it's expecting version 1.1.36 being loaded, but it gets version 1.1.36.

 

I've looked just about anywhere in the project, but I can't locate the reason it expects version 1.1.36.

 

Does anyone here have an idea?