In my space, there are two databases that both share the same single-select field. Both databases are added to timeline view. In timeline view, there’s the option to create “lanes.” It lets me choose the single-select field to make lanes, in addition to the default, “Created By.” I can create these lanes using “Created By” but when I choose my single-select field, it doesn’t go through.
Before:
To add to this (or perhaps it’s the same issue) - when multiple databases are selected in the Timeline view, I can no longer select all relevant fields from the first database as possible lanes - it only gives me those from the second one. Even if they are re-ordered.
You are only allowed to choose fields that exist in both dbs. Otherwise, if you chose a field for grouping that only existed in the first db, it would be impossible to know in which group to put items from the second db.