Hi,
I was able to get them both ticked by first installing and making a build with just Google ARCore to make sure the images and tracking worked. Then I installed Lightship from the git URL and made a new built o test whether just adding Lightship was causing the problem the build still worked and the Niantic Lightship SDK + Google ARCore was still unchecked.
Then while leaving the base Google ARCore checked I also checked Niantic Lightship SDK + Google ARCore which didn’t try to uncheck the plain Google ARCore. I then made a build like that and it all seemed to work.
I have since unchecked the Google ARCore and the project still builds and works properly. It now also prevents me from being able to check Google ARCore when I have Lightship enabled.