One of the issues with Chase Ultimate Rewards travel portal was that it didn’t clearly state what fares were basic economy/regular economy so it was difficult to determine if a fare included things like seat assignment and possibility of an upgrade for elites. This is especially annoying as booking through the travel portal makes your Chase Ultimate Rewards points worth 1.25¢ each when you hold the Chase Sapphire Preferred or 1.5¢ each when you hold the Chase Sapphire Reserve.
Chase has now fixed this issue and it will clearly show fares that are basic economy, “main cabin” and premium seats.
Hat tip to /r/churning