Incorrect intelliSense errors depending on include order

Bug type: Language Service

Describe the bug

• OS and Version: Windows 10 21H2
• VS Code Version: 1.68.1
• C/C++ Extension Version: 1.10.7
• A clear and concise description of what the bug is, including information about the workspace (i.e. is the workspace a single project or multiple projects, size of the project, etc).

I've got the following two files, using IAR Systems standard library headers:

// main.cpp
#include <stdint.h>
#include <wchar.h>
#include <memory>

#include "header.hpp"
int main() {
  auto b = ns::B(1);
}

// header.hpp
#pragma once

namespace ns {
  class B {
    public:
      explicit B(const int& a) {}
  };
}

In main.cpp, intelliSense incorrectly complains that the namespace ns does not exist:

If I open header.hpp, where ns is defined, and go back to main.cpp, the error disappears for a while. If I browse some other files for a while, the error reappears.

Interestingly, the problem only occurs when <memory> is included last of the standard library headers. Removing any of the includes or including <memory> earlier gets rid of the intelliSense error. main.cpp compiles correctly in all cases.

Steps to reproduce
Here is an example that reproduces the problem:
cpptools_errors_from_include_order_example.zip
It includes all the necessary files, including the c_cpp_properties.json and all required IAR standard library headers.

Simply open main.cpp and observe the intelliSense error.

Additional context
This may be related to https://github.com/microsoft/vscode-cpptools/issues/9170. The symptoms are similar, but the workaround of disabling the cache size limit did not work for me.

Open the supplied cpptools_errors_from_include_order_example.zip and inspect main.cpp, header.hpp, c_cpp_properties.json, and the IAR headers; start by reproducing the false ns error with included last. Done means IntelliSense no longer reports that ns does not exist for the provided example, while the project still compiles correctly.