Issue detected:
The default community folder is encrypted (Win 11 Pro) and I’ve been unable to open files within those (sub)folders, i. e. the manifest.json. Navigraph Hub and the MSFS 2024 itself obviously had the same problem and couldn’t access those encrypted files.
Workaround:
I changed the default location of the community folder from %USERPROFILE%\AppData\Local\Packages\Microsoft.Limitless_8wekyb3d8bbwe\LocalCache\Packages to another drive/location.