Oh my god. Are you kidding me. That's incredibly embarassing. As you say, I must have pressed Alt + D after taking the screenshot of the planner details out of habit. And I must have pressed Alt + D or used the wrong planner the other times I noticed this, too. I'm very sorry for wasting your time ...

Welll it does select both trees and fish even though I have "trees/rock" checked

EDIT: I was wrong, this was just an idiotic error on my part.

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The wiki article on this states that "Fish and cliffs are not included in this filter", which is ambiguous to me; do they mean that fish/cliffs shouldn't be marked (not current behaviour), or that fish/cliffs are not excluded ...