I've invalidated the cache a ton try try and get this IDEA error to go away but haven't found any solutions yet.
As you can see from the auto complete the Option[Brand] has the exists method: http://cl.ly/image/2P3I2T0u183e
But once I get done typing the code I get a big old underline saying Unable to resolve symbol exists: http://cl.ly/image/3K3Y3d1E2T2p
There's slightly more information if you can hover on that red area to the right: http://cl.ly/image/2N0g2B2C2F39
Not sure if the type of the Expected (Brand) => Boolean vs Actual (model.Brand) = Boolean is somehow different.
I'm running 12.1 CE and Nightly scala - I've had this problem for over a week.