MSBuild - want to get the output assembly - visual-studio

Question

I have a .targets file in a folder named .pack I have this:
<PropertyGroup>
<TaskAssembly>$(OutputPath)netstandard2.1\Test.dll</TaskAssembly>
</PropertyGroup>
Why instead of MyProject\bin\Debug\netstandard2.1\MyProject.dll it locates like the below line?
MyProject\.pack\bin\Debug\netstandard2.1\MyProject.dll
Why .pack is there!?
Then wanted to use it with a Using task
<UsingTask
TaskName="brand.ProBuild.Tasks.TestFunction"
AssemblyFile="$(TaskAssembly)"
/>
Defined as inline address, played with slashes, cleared bin/obj, restarted, don't why it can't understand some addresses.
Defined and used several path variables in my targets files, some working correctly and some are troublesome especially when want to use parents or some problems with slashes '/', don't know maybe some addresses are working randomly. But what is wrong with the $(OutputPath) ?!
Visual-studio 2019, .Net Standard 2.1 (It has multiple targets I want to get that specific dll)

Answer 1

You should check in your main project, before the import node like <Import Project=".pack\xxx.targets" />, check whether you defined the outputpath property again like
<outputpath>.pack\bin\Debug\</outputpath>
Suggestion
From your description, you created a custom MSBuild task dll to use its new custom task in another project, first, please make sure that the Test.dll is in the output folder of your project called MyProject.
Then, check whether you have redefined the outputpath before the import xml node.
Like this:
<PropertyGroup>
<outputpath>.pack\bin\Debug\</outputpath>
</PropertyGroup>
..........
<Import Project=".pack\xxx.targets" />
........
<UsingTask
TaskName="brand.ProBuild.Tasks.TestFunction"
AssemblyFile="$(TaskAssembly)"
/>
If so, you should change OutputPath to bin\Debug\.
In addition, if it does not help you, please share the xxx.csproj of project MyProject with us so that we can troubleshoot your issue more quickly.
Update 1
Since you have only one targets file in your project, I suggest you could follow these suggestions:
1) close VS Instance, enter your project folder, delete the .vs hidden folder under the solution folder, bin and obj folder. Then ,restart your project to test again.
2) you can define the correct value in the xxx.csproj file before the imports xml node to force the correct value of outputPath.
<PropertyGroup Condition="'$(Configuration)'=='Debug'">
<OutputPath>bin\Debug\</OutputPath>
</PropertyGroup>
<PropertyGroup Condition="'$(Configuration)'=='Release'">
<OutputPath>bin\Release\</OutputPath>
</PropertyGroup>
.......
<Import Project="xxx.targets"/>