In the Relationship view, If you zoom in using the mouse wheel and shift, or the zoom slider, the scroll bars to the side and bottom of the view are lost, and the diagram move off of the visible area.
This should be enabled in conjunction with a fix for panning and selecting in the relationship view https://ideas.powerbi.com/forums/265200-power-bi-ideas/suggestions/37891429-hand-tool-for-relationship-view