I've deployed a fresh install of the latest typo3 through composer on windows-based machine. All works fine except image processing: I've installed ImageMagick, but the tests fail to execute with message:

Image generation failed ImageMagick / GraphicsMagick handling is enabled, but the execute command returned an error. Please check your settings, especially ['GFX']['processor_path'] and ensure Ghostscript is installed on your server. Also ensure that possible codecs needed for specific image/video formats are available on your system.

If I run the commands manually - everything works fine. System has access to temp folder as I see that install Tool generates other test images there (e.g. Gdlib tests run ok) Any ideas?

UPD: regarding a similar question here: TYPO3 9 - Image generation failed - ImageMagick / GraphicsMagick handling is enabled, but the execute command returned an error - there the command fails to run manually, while in my case it works. Moreover, I've created a test .php file in typo3 public folder with just one line of code:

exec('"C:/ImageMagick-6.9.13-Q16/convert.exe" -auto-orient "+profile" "*" -auto-orient -geometry 300x225! -quality 85 -colorspace ...')

and it works fine (a file gets created)

UPD2: added var_dump as suggested in comments:

{
    "success":true,
    "status":[
        {
            "severity":2,
            "title":"Image generation failed",
            "message":"ImageMagick / GraphicsMagick handling is enabled, but the execute command returned an error. Please check your settings, especially [\u0027GFX\u0027][\u0027processor_path\u0027] and ensure Ghostscript is installed on your server. Also ensure that possible codecs needed for specific image/video formats are available on your system.",
            "storeInSession":false
        }
    ],
    "command":[
        [
            "C:/inetpub/wwwroot/test13/public/typo3temp/assets/images/installTool-read67ea3dbed9112110967828-jpg.jpg",
            "\u0022C:/ImageMagick-6.9.13-Q16/convert.exe\u0022 -auto-orient \u0022+profile\u0022 \u0022*\u0022 -auto-orient -geometry 300x225! -quality 85 -colorspace \u0022sRGB\u0022 \u0022jpg:C:/inetpub/wwwroot/test13/vendor/typo3/cms-install/Resources/Public/Images/TestInput/Test.jpg[0]\u0022 \u0022C:/inetpub/wwwroot/test13/public/typo3temp/assets/images/installTool-read67ea3dbed9112110967828-jpg.jpg\u0022"
        ]
    ]
}

UPD3: Folders access: access