Rails 4.2 Asset Pipeline issue

[coding-red-panda]

Hello,

I'm trying to get this gem to work under an old Rails 4.2 project, but I keep getting issues with the asset pipeline.
It's complaining with Sprockets::Rails::Helper::AssetNotPrecompiled in CASino::Sessions#new

So basically it's telling me that <%= stylesheet_link_tag 'sessions/new' %> in the view is not precompiled.
Shouldn't this be picked up automatically?