Warner Bros and Rocksteady have released a new 548MB patch for Batman: Arkham Knight. This patch will be auto-downloaded from Steam, and you can read its full changelog below.

Fixed some issues with stars being awarded or lost incorrectly in specific AR Challenges
Improved target prioritization during combat
Restored heavier rain during the opening section of the game
Fixed missing rain effects on a few remaining player character skins
Miscellaneous gameplay fixes and stability improvements
Fixes to some keyboard and mouse prompts after being rebound
Made frame times more consistent for 60hz monitors running at 30fps with VSync enabled
Previously equipped gadgets can be selected with keyboard and mouse again after restarting an AR Challenge
Fixed the default key binding for Harley’s Snare gadget
Batgirl’s Remote Hacking Device can now be properly selected with keyboard & mouse in AR Challenges
Minor performance optimizations for certain combinations of hardware
Fixed keyboard & mouse controls that did not function in DLC AR Challenges when no previous save data existed
Quick Photo Mode can now be triggered with keyboard and mouse controls when using the Batmobile
Special Combo Takedowns can now be performed with Quickfire Gadget binds if they were rebound
Fixed graphical corruption that may occur after Alt-Tabbing
Improvements and corrections to some localized text
Added new Classic Harley Quinn skin for use in AR Challenges & the Harley Quinn Story Pack
Added Arkham Knight as a playable character for AR Challenges & the Red Hood Story Pack
Added support for December DLC content