After installing and connecting to spacedesk, the mouse on the primary display becomes unusable.
For example, if spacedesk as secondary is on the right, the mouse is in the correct position on the primary on the left, but as it travels to toward the secondary, it it disappears before it gets to the edge.
It appears to be scaled to the primary display less the spacedesk screen. If primary is 2560x1440 and secondary is 1024x768, when the mouse cursor reaches 2560-1024 (1536), the mouse shows up on the secondary, and disappears from the primary.
It's as if the display position of the cursor vs where Windows thinks the mouse is located is different.