I was playing around with folder navigation options tonight. I was using the defaults for Alfred 3, so I enabled Use <- and -> for folder navigation under Features > File Search. I tried it out and decided I didn't like it so I unchecked the option to revert Alfred 3 to the default behavior for <- and -> when navigating folders.
After unchecking the option, the behavior didn't revert to the default of showing me the action panel when I pressed -> on a folder. It did stop the -> from navigating into the folder, but the -> had no other effect. I did a quit and restart of Alfred 3 and the problem persisted.
Entirely possible this is PEBKAC as I'm fairly new to Alfred, coming to it from many years as a LaunchBar user. But this seems like it might be a bug in that option deselect call back.