The maximize size of a window at the lowest software layer in Windows is limited to a maximum height of 2^15-1 pixels (32K pixels). Most software that needs to present long, scrolling lists to the user repaints the window with the current view into the list. For example, the LR Library grid view does that as you scroll thumbnails (logically, the grid view can be much, much larger than 32K pixels high). Higher-level user-interface libraries typically handle all of this repainting for the application developer; but it appears that for some user-interface controls in Windows LR, the Adobe developers neglected to do that (perhaps because Windows LR doesn't use any of the common higher-level libraries).
The 32K limit has been in place since at least Windows 3. It's not at all uncommon for window systems to have such limits at the lowest levels, relying on higher levels of the software to provide infinite scrolling views. So I think it's very unlikely Microsoft will ever change it, at least not until we have 32K displays :->