Problems with a project

BallonBrian​: That's great advice from ronald-hicks​. I'll just add this: the best 
practices for uploading a .story file.

• Only include slides that are related to the problem.
• Be sure objects, layers, motion paths, and variables have meaningful names.
• If there is proprietary content, replace or delete it. For example, replace 
  proprietary text with “ipsum lorem” text. 

That "works at 10, breaks at 12" pattern is a useful clue — it almost always means something was built around the number 10 specifically, not the cards themselves. Usual suspects:

 

- A trigger condition or variable comparison that hardcodes 10 (e.g., when cardCount = 10, show the results layer) and never got updated.

- The two new cards aren't fully wired — duplicated cards sometimes arrive missing a state, a trigger, or a layer reference the originals had.

 

Quick way to narrow it: test with 11 cards. If 11 works and 12 breaks, diff card 12 against card 10 trigger by trigger. If 11 breaks too, the count logic is the culprit.

 

And yes — attach the .story file to the thread if you can. Much faster than guessing.