Including files generated inside PostBuildEvent into ClickOnce deployment happens in race condition and sometimes doesn't work correctly

Question

I have a WPF project. Its .csproj file contains a <PostBuildEvent> - there runs a script which produces some extra files. The size of one of them is almost 20 MB, and the project itself is pretty large - it may be important to reproduce the issue.

I would like to deploy these files along with the project via ClickOnce. So later in the .csproj I write:

<Content Include="$(PathToDirectoryWithProducedFiles)\**\*">
    <Link>$(PathRelativeToOutput)\%(RecursiveDir)%(Filename)%(Extension)</Link>
    <Visible>false</Visible>
</Content>

This does usually work, but not always. Sometimes the files just are not put into the publish folder, and sometimes ClickOnce installer produces an error "File, [filewhichweights20MB], has a different computed hash than specified in manifest".

I have a clear feeling there is a race condition between ClickOnce deployment process and the script inside <PostBuildEvent>. Sometimes the script produces all files in time, and sometimes ClickOnce tries to copy the directory before they are completely generated.

I've tried to specify each file in different <Content> tags separately, but it doesn't work. Moreover, in theory there may be a situtation when the script produces different files, so this workaround will become useless.

The questions are:

• When (after what stage of build process) does ClickOnce exactly copy <Content> files and folders into the publish folder?
• Why there is a race condition there, as in theory <PostBuildEvent> is a part of build process?
• [The main one] How do I include files produced inside the <PostBuildEvent> script into the deploy correctly to get rid of infrequent but very annoying deployment errors? (And not to use mage.exe as using it would be more complicated)