QSharedMemory doesn't work as described for Mac AppStore builds

QSharedMemory does not work as described at https://doc.qt.io/qt-6/qsharedmemory.html#details - see notes for Apple Platforms.

Minimal example which reproduces the problem:

https://github.com/itay-grudev/SingleApplication/tree/master/examples/basic

Note: to test the above example, singleapplication_p.cpp should be patched to assign

blockServerName = "<apple_team_id>.myapp/shared"; 

in the function genBlockServerName(), as per the Qt docs linked to above.

Expected result:

Application loads and runs as usual.

Actual Result:

Application crashes on startup with this message in terminal:

SingleApplication: Unable to create block.
SingleApplication: 1 "QSharedMemoryPrivate::initKey: unable to set key on lock"

Tested with:

• Qt 6.3.2 built with `-feature-ipc_posix` enabled
• AppStore Connect resources created:

• • Developer ID Application certificate
  • Application ID
  • Application Group ID
  • Provisioning Profile
• shmem key formatted as per documentation, ensuring <30 chars, ie "XXX1XX11XX.myapp/shared"

Reference:

See discussion at: https://github.com/itay-grudev/SingleApplication/issues/136