Here is another example, I've opened a notepad and wrote in it "I'm testing ScreenPad+ Asus UX581GV". if you can't see the full text, it means that part of it is under the taskbar.
Here, I've set the taskbar to left side, and then I've placed a notepad on the first 1/3 part of the screen, by dragging the app and releasing it on the hot spot. As you can see, part of the Notepad goes under the taskbar which is clearly a bug.
Here, I've set the taskbar on top, and you should be able to see the app menu, and the option to maximize, minimize, and close. As you can see, you can't, because ScreenPad+ place the app under the Windows taskbar, ignoring it completely.
Now, if this issue will actually be fixed by the dev team, they should consider also that the taskbar can be rescaled the user, so they need to get the actual size of the taskbar and offset everything using that value, and not hardcoding a default value.