Platform (cmake.platform) and toolset (cmake.toolset) options are not passed to CMake and/or active kit ignored when generator is set explicitly

Brief Issue Summary

I am trying to configure a project to be built with Visual Studio 2019 using a non-default toolchain (MSVC 2015 amd64), but cannot achieve the required configuration command via VSCode interface and CMake Tools configuration.

As far as I understood, it should work by selecting a kit and/or or by configuring generator / platform / toolset in the settings, but neither option gives the desired result.

Expected

When launching cmake manually as the following:
D:\DevTools\CMake\bin\cmake.EXE --no-warn-unused-cli -DSTATIC:STRING=ON -DBUILD_UNIT_TESTS:STRING=ON -DCMAKE_EXPORT_COMPILE_COMMANDS:BOOL=TRUE -Hd:/Source -Bd:/Source/build -G "Visual Studio 16 2019" -A x64 -T v140

I get:

-- The C compiler identification is MSVC 19.0.24245.0
-- The CXX compiler identification is MSVC 19.0.24245.0

Apparent Behavior:

1. Command palette / CMake: Select a Kit / "VisualStudio.14.0 - amd64".
2. Set the following configuration in CMake Tools / Extension Settings:
   "cmake.generator": "Visual Studio 16 2019",
   "cmake.platform": "x64",
   "cmake.toolset": "v140"
3. Command palette / CMake: Delete Cache and Reconfigure

[proc] Executing command: D:\DevTools\CMake\bin\cmake.EXE --no-warn-unused-cli -DSTATIC:STRING=ON -DBUILD_UNIT_TESTS:STRING=ON -DCMAKE_EXPORT_COMPILE_COMMANDS:BOOL=TRUE -Hd:/Source -Bd:/Source/build -G "Visual Studio 16 2019"

-A and -T options are missing, so the default toolchain for Visual Studio 2019 is used:

[cmake] -- The C compiler identification is MSVC 19.26.28806.0
[cmake] -- The CXX compiler identification is MSVC 19.26.28806.

Other tested options

I get the same result if platform and toolset are omitted, and/or if cmake.ignoreKitEnv is selected.

I could override the configuration by passing -A x64 -T v140 via cmake.configureArgs, but when I close and reopen VSCode they appear twice on the command line, which results in a cmake error:

[proc] Executing command: D:\DevTools\CMake\bin\cmake.EXE --no-warn-unused-cli -A x64 -T v140 -DSTATIC:STRING=ON -DBUILD_UNIT_TESTS:STRING=ON -DCMAKE_EXPORT_COMPILE_COMMANDS:BOOL=TRUE -Hd:/Source -Bd:/Source/build -G "Visual Studio 16 2019" -T v140 -A x64
[cmake] Not searching for unused variables given on the command line.
[cmake] CMake Error: Multiple -T options not allowed

Platform and Versions

• Operating System: Windows 10
• CMake Version: 3.17.3
• VSCode Version: 1.46.1
• CMake Tools Extension Version: 1.4.1
• Compiler/Toolchain: Visual Studio 2019 and Visual C++ 2015