When building I get the error message "Placeholder is in the way" and it blocks me from building over it, even with super force build.

https://imgur.com/a/3Mridjz

I don't know what those placeholders are, and I've never seen this, so you'll have to provide some reproduction steps.

Here is the save file: https://drive.google.com/file/d/19TPOyPDvJm29FUmHfEb-Ea05poFJnAEV/view?usp=drive_link

I cleared the sandbox and circled the invisible entities. At the same time, I see some tracks that I can't delete (red dots in map view).

I don't have access to that file.

Sorry, the link is public now.

Basically, the Construction Planner mod does not play nicely with this mod, and it is not configurable/interactable enough for me to resolve the issues. Both of these mods do similar things behind-the-scenes, so it's easy for conflicts to arise. Your best bet is to make the author of that mod aware of this one, and either expose some APIs for other mods to use to prevent this from happening, or internally prevent it from happening in this case.

Thank you for the feedback. Maybe I can try the other construction planner: https://mods.factorio.com/mod/ConstructionPlannerContinued