Repro: Make a part, put an attachment inside the part, now put the part inside game.ServerStorage. Drag a selection box over the attachment position and it will still be selected even though it’s not in workspace.
Also note: Constraint Details must be enabled for the bug to occur. (setting is found under Model tab in the constraints section)
Can confirm. It’s incredibly annoying for my workflow (it would also be nice to have an ability to “lock” workspace attachments and constraints as well).