First of all sorry If I have put this issue in the wrong category but I am having a hard time figuring out what component causes the issue because there are multiple at play.

I have KDE Neon with all updates installed (5.10.5 at this moment). If I put a vertical task manager (I have tried every type in the alternatives) on the edge of a monitor that's closest to the other monitor and after that proceed to drag a window to the half that's farthest to monitor with the vertical task manager it disappears.

I know it's a bit hard to understand so I made a video showing the issue here https://drive.google.com/open?id=0BxK93EA-4fGUMWx0bWlzUXBlNVU
Because the video is like 8MB in size I could not attach it here (limit of approx 4MB).

I have tried a fresh install of Neon with only 1 task manager, 2 task mangers, every rendering method available but the issue persists.

I reproduced this issue on 2 separate computers, 1 with an Intel HD620 iGPU and one with an Nvidia Geforce GT 730. If needed I have a computer with an AMD card too for testing, but I don't have 2 monitors on it at the moment.