@BenLee, it’s not a huge deal, I just wanted to share so Coda team is aware of this behavior.
I understand that I can delete values from the column, but you can imagine if the table is big — it’s a big task to delete and select correct values for all the rows.
By the way, to give you context why I tried to change Lookup type column to List type column: because when grouping a table by text values from the list you can choose which groups to show even if they don’t have any rows currently (with the pin button in the grouping settings) and filter out groups that you don’t want to show (with the table filter).
The fact that you can’t set pins (“always show this group”) and filter out unwanted groups when you are grouping by the lookup column is killing me and makes project management system that I’m building in Coda much more difficult to create.
It’s double pain when you group by two lookup columns (Initiatives and Projects in Tasks table in my system).
Are you thinking about extending grouping settings to lookup groups in some near future?
Here is a post in Suggestion Box about same problem from another user: