This also affects Ubuntu 17.10 which uses Wayland by default.

The mouse cursor is visible and I can move it with my USB mouse. I can send keyboard input from the UR app, but when I try to move the mouse cursor from UR the cursor itself doesn't move but it seems like there's a second, invisible cursor moving around because I'm actually able to highlight items on the screen and click independent of the "main" cursor - it's just very hard to tell where I'm pointing without a visible cursor!

When I select the Xorg fallback session on the login screen UR works as normal.