System Information
Operating system:W10
Graphics card:GTX970
Blender Version
Broken: 2.80 26d5a3625ed 2018 11 29
Short description of error
"Shared location" leaves some vertex behind...
Exact steps for others to reproduce the error
Open blender
Open UV editing tab
Enter edit mode and select a vertex from the center of the cube's uv and move it, it will either pick one vertex connected by 3 edges, or one connected by 2, but not a single one conected by the four edges