System.IO.FileLoadException, cant find an assembly, assembly version conflict

I have 2 solutions in one project. One of the solutions is a unit test project, they both have the same Newtonsoft.Json package version.

This is the location with the csproj file where the package is installed:

   <Reference Include="Newtonsoft.Json, Version=12.0.0.0, Culture=neutral, PublicKeyToken=30ad4fe6b2a6aeed, processorArchitecture=MSIL">
      <HintPath>..\packages\Newtonsoft.Json.12.0.3\lib\net45\Newtonsoft.Json.dll</HintPath>
    </Reference>

If I change the version to 12.0.3, the solution isnt able to find Newtonsoft class anymore.

Full error message.

System.IO.FileLoadException: 'Could not load file or assembly 'Newtonsoft.Json, Version=12.0.3.0, Culture=neutral, PublicKeyToken=30ad4fe6b2a6aeed' or one of its dependencies. The located assembly's manifest definition does not match the assembly reference. (Exception from HRESULT: 0x80131040)'

My packages.config file:

 <?xml version="1.0" encoding="utf-8"?>
<packages>
  <package id="FSharp.Core" version="4.5.2" targetFramework="net461" />
  <package id="HtmlAgilityPack" version="1.7.4" targetFramework="net461" />
  <package id="Newtonsoft.Json" version="12.0.3" targetFramework="net461" />
  <package id="RestSharp" version="106.6.10" targetFramework="net461" />
  <package id="ScrapySharp" version="3.0.0" targetFramework="net461" />
  <package id="System.Runtime.Caching" version="4.5.0" targetFramework="net461" />
</packages>

I tried to reinstall the pack and clean, rebuild and close and open my visual studio. It gives the same error. I dont understand what VS2019 tries to do behind the scenes, but it doesnt find the dll.

This is what I get after the re-install the package,

   <Reference Include="Newtonsoft.Json, Version=12.0.0.0, Culture=neutral, PublicKeyToken=30ad4fe6b2a6aeed, processorArchitecture=MSIL">
      <HintPath>..\packages\Newtonsoft.Json.12.0.3\lib\net45\Newtonsoft.Json.dll</HintPath>
    </Reference>

It keeps adding this. Why hte version is 12.0.0.0

I have used AsmSpy.exe (available in NuGet) to analyze this type of problem. It looks at all the libraries and their dependencies and reports on inconsistencies.