I have two base searches in a dashboard, not sure if that is at all possible. But as soon as i use the second base search created, i get warnings with this :
Warning is : Unknown node is not allowed here. Before creating the second base search this warning was not existing.
You're exactly right, @macadminrohit . Base searches only require earliest and latest in the base search itself and do not expect them to be called out in any of the searches referencing them. I will move your comment to an answer if you'd like to accept it and close out the question.
I think the time picker should also be included in your base search. So that its something like this. What do you currently have?
"base search query"