If I set QT_DEBUG_PLUGINS=1 output is below.

56: Found metadata in lib /opt/qt5/plugins/platforms/libqqnx.so, metadata= ...
...
75: loaded library "/opt/qt5/plugins/platforms/libqqnx.so"
...
78: QLibraryPrivate::loadPlugin failed on "/opt/qt5/plugins/platforms/libqqnx.so" : "Cannot load library /opt/qt5/
plugins/platforms/libqqnx.so: (Library cannot be found)"

As output message, looks like some modules found libqqnx.so but QLibraryPrivate didn't.
I'll post additional info if I figure out more about that.
Any help would be appreciated.


<Full output log>

slog2_api: cannot connect to slogger2 server...errno=No such file or directory
Error registering slogger2 buffer!
QFactoryLoader::QFactoryLoader() checking directory path "/root/qt5test/platforms" ...
slog2_api: cannot connect to slogger2 server...errno=No such file or directory
Error registering slogger2 buffer!
QFactoryLoader::QFactoryLoader() checking directory path "/opt/qt5/plugins/platforms" ...
slog2_api: cannot connect to slogger2 server...errno=No such file or directory
Error registering slogger2 buffer!
QFactoryLoader::QFactoryLoader() looking at "/opt/qt5/plugins/platforms/libqminimal.so"
slog2_api: cannot connect to slogger2 server...errno=No such file or directory
Error registering slogger2 buffer!
Found metadata in lib /opt/qt5/plugins/platforms/libqminimal.so, metadata=
{
    "IID": "org.qt-project.Qt.QPA.QPlatformIntegrationFactoryInterface.5.2",
    "MetaData": {
        "Keys": [
            "minimal"
        ]
    },
    "className": "QMinimalIntegrationPlugin",
    "debug": false,
    "version": 328449
}


slog2_api: cannot connect to slogger2 server...errno=No such file or directory
Error registering slogger2 buffer!
Got keys from plugin meta data ("minimal")
slog2_api: cannot connect to slogger2 server...errno=No such file or directory
Error registering slogger2 buffer!
QFactoryLoader::QFactoryLoader() looking at "/opt/qt5/plugins/platforms/libqoffscreen.so"
slog2_api: cannot connect to slogger2 server...errno=No such file or directory
Error registering slogger2 buffer!
Found metadata in lib /opt/qt5/plugins/platforms/libqoffscreen.so, metadata=
{
    "IID": "org.qt-project.Qt.QPA.QPlatformIntegrationFactoryInterface.5.2",
    "MetaData": {
        "Keys": [
            "offscreen"
        ]
    },
    "className": "QOffscreenIntegrationPlugin",
    "debug": false,
    "version": 328449
}


slog2_api: cannot connect to slogger2 server...errno=No such file or directory
Error registering slogger2 buffer!
Got keys from plugin meta data ("offscreen")
slog2_api: cannot connect to slogger2 server...errno=No such file or directory
Error registering slogger2 buffer!
QFactoryLoader::QFactoryLoader() looking at "/opt/qt5/plugins/platforms/libqqnx.so"
slog2_api: cannot connect to slogger2 server...errno=No such file or directory
Error registering slogger2 buffer!
Found metadata in lib /opt/qt5/plugins/platforms/libqqnx.so, metadata=
{
    "IID": "org.qt-project.Qt.QPA.QPlatformIntegrationFactoryInterface.5.2",
    "MetaData": {
        "Keys": [
            "qnx"
        ]
    },
    "className": "QQnxIntegrationPlugin",
    "debug": false,
    "version": 328449
}


slog2_api: cannot connect to slogger2 server...errno=No such file or directory
Error registering slogger2 buffer!
Got keys from plugin meta data ("qnx")
slog2_api: cannot connect to slogger2 server...errno=No such file or directory
Error registering slogger2 buffer!
loaded library "/opt/qt5/plugins/platforms/libqqnx.so"
slog2_api: cannot connect to slogger2 server...errno=No such file or directory
Error registering slogger2 buffer!
QLibraryPrivate::loadPlugin failed on "/opt/qt5/plugins/platforms/libqqnx.so" : "Cannot load library /opt/qt5/plugins/
platforms/libqqnx.so: (Library cannot be found)"
slog2_api: cannot connect to slogger2 server...errno=No such file or directory
Error registering slogger2...