Unable to resize windows on split full screen in MacOS Mojave when using external monitor

Solution 1:

WORKAROUND: Read somewhere that to get (temporarily) the resizing bar, you drag one of the split windows by the title to the other side of the monitor. The bar will remain for a while. Resize, and if needed, switch back the windows. It has been working for me on an external LG monitor in Mojave.

Solution 2:

I found that if you simply click the title bar you'll be able to drag the windows after, for a few seconds.

I believe that this is intentional to prevent changes to the screen split by mistake.

So it's possible that this is by design.

Solution 3:

I have the same issue… I’m working around it by resizing the windows in split view on the MacBook screen and only then dragging them to the external monitor, but this "solution" is obviously far from perfect :/ Hope they fix this soon.