Diagnosis
Hard water combined with insufficient rinse aid. The film is dried mineral residue.
How to Fix It
Fill the rinse aid dispenser (the cap next to the detergent cup) to the MAX line. Set the rinse aid dial to level 4 or 5. Use a good quality rinse aid like Finish Jet-Dry; it's non-negotiable with hard water. Also, ensure you're using a detergent designed for hard water.
If That Didn't Work
Your water might be extremely hard. Check if the internal water softener needs salt—this model doesn't have a user-serviceable salt reservoir. If hardness is severe, you may need to install a whole-house softener or use a dishwasher cleaner product monthly to dissolve scale.
Heads Up
Never use powdered detergent in this model if you have hard water; it exacerbates the filming. Use pods or gel only.