I'm experiencing the same issue. The OK button in the default Mendix pop-up message isn't visible. Only when you click on it, you can see the hover in gray.
I've updated to the latest version 10.18.5 and the problem persists.
Is there any way to change the style of that pop-up?
Hello Ivan,
If you go to your Studio pro, Structure mode, you click twice on the button you will see a dialog where the Button style is present.
Try to change this style. Or in the right pane of Studio pro you can see the style panel also.
In case you change the style and the button is visible, it means that you only need to change the color.
In case this button is not visible still, then check if you have created a logic(Microflow or nanoflow) and you haven't given access to that user to click on that button to trigger the logic.
Let me know in case you need more help :)