Hello, reading the patch notes i thought this would be addressed, but it might be a different issue, as shown in the screenshot here:
Some tiles (seems pretty random) cannot be removed
main active mods: Space Exploration, Krastorio2, Landfill plus 1.0.13
everything is up to date @12-Jun-2021

https://ibb.co/qytJnqG

I also tried to delete the surface and try again, same result
(note: i started this playthrough with an earlier version of landfill, then updated, if that matters, but the landfills in the screenshot have been placed with latest version)