Qt 5.14.2+Qt 4.12.0
Very basic code using QtCreator:

1. add QPushButton, QLabel using creator.
2. right click on QPushButton->go to slot — add code: ui->label->setText("whatever");
3. build->run, button does NOT change the label text

Few comments:

• The same procedure with the same version Qt+QtCreator produces a working app on Linux, and on Windows.ie. text changes.
• Trying to change the text on the QButton works, also on MacOS.
• Tried adding private slot manually, connect in the MainWindow constructor, still does NOT work on MacOS (works on Linux, Windows).
• Tried right click on MainWindow->add slot-> connect via signal/slot editor in QtCreator and code in mainwindow.cpp. Does not work on MacOS, but works on Linux, Windows.

I have no idea where the problem lies.

Will upload the directory where the code resides.

I do think that Qt is a great platform, and is unique in providing a common IDE for all, with support for Android too. I hope the great work continues to flourish.

First time reporting a Qt bug - sorry if I did not follow the proper mannerisms.
Ken Aoki.