Hello, I am trying to start a rectangle corner from where these two lines intersect. Before I could hover over the end point and could move away and it would track the end (highlights yellow if I remember). I may have disabled a feature by accident but not sure.
If the two lines actually do intersect, you can use the Int object snap - check the osnap boxes). If you are trying to snap to the virtual intersection of lines that don’t actually meet, perhaps the SmartTrack feature is what you are looking for (activate it via the status bar).