This bug was introduced with 7.0 and persists into 7.2.2. It has been reproduced using both Chrome and Microsoft Edge 

Steps to reproduce:

1. Create a new map with links between two objects or edit and existing map with links
2. Add a line type shape to the map and save the map
3. Exit the map editor and view the map

Result:
Neither the new line type shape or any of the links are visible 

Expected:
Line and links should be visible.