.NET sandboxed app on macOS does not see certificate in keychain imported by third party sandboxed app

[tsw-github]

Hello,
we have a dotnet application (.NET 10, C#14) that uses the SescureBlackbox libraries (v24.0.9470) to access the macOS (v26.2, M3) keychain. The application runs within the macOS platform in a sandbox, because we need it to communicate with the Safari web browser extension via App Groups, the application is not distributed via the App Store. We have currently noticed a problem that when a third-party application eToken (https://www.602.cz/e-token), which also runs in a sandbox and does not share an App Group or Keychain group with our application, issues a certificate and imports it into the keychain, our application does not see it. When we disable the sandbox for our application, we see the certificate fine. When we create a simple test application via XCode/Swift, it always sees the certificate in the keychain, whether it has sandbox enabled or not. Do you know what the problem could be? Thank you.