Repro is with Brim commit c36fada.

As shown in the attached video, if a user chooses to type out a from in a Query Session rather than using a "From Pin", then they brush the bar chart, they get the "pool name missing" error. A "fix" would be for the user to turn their from into a pin and move it in front of the Time Range pin that was created by the brush of the bar chart, but this may be too subtle/complex for both new users and users of the prior Brim app experience where the from was effectively handled for them behind the scenes.

It's been proposed that we could do some clever things to recognize this case and effectively move the typed-out from to the front of the query that's issued on the backend, so to the user it seems to "just work".