Caused by rB4212b6528af. outlineColor is computed by the vertex shader, so not a uniform. So outlineColor was undefined. note: it was still possible to run into the situation that a selected UV is drawn ontop of a selected pinned UV [you had to disable sticky selection for this], now also make sure selected-pinned are drawn topmost, then selected, then unselected UVs. Maniphest Tasks: T83361 Differential Revision: https://developer.blender.org/D9786