Cool, didn't see it in the list... will look harder next time. All Rails signals were affected.

After placing a blueprint with a yellow belt.
Tried removing yellow belt ghost, does not work, will not even highlight.
Tried removing other yellow items, spliter and underground belt worked and highlighted as expected.

A much easier way is to open your old save, move all your blueprints to the Blueprint tool in .15.x and store it in "My Blueprints". Save your game and load you new/current .15.x save and TaDa the Blueprints are in "My Blueprints" for all you games going forward. I used this meth...