Hi Ziqiao, understood. I'll file a new report about it. I appreciate your attention to this and your suggestions to try to resolve it. Hopefully the feedback report gets some attention.

For more context: I did further testing using exclusionPaths and this bug reliably occurs with ANY exclusion path occurring within the top 13 points of the second container. Any exclusion path there - even one just 1pt by 1pt - will cause ALL of the text to lay out into the first container, overlapping itself. I.e., the exclusion path NSBezierPath(rect: CGRect(x: 0, y: 13, width: 1, height: 1)) causes the same bug as the code above that uses CGRect(x: 0, y: 0, width: 306, height: 648).

Thank you! I've made the Feedback report. The FB number is FB17597711.

Hi Ziqiao, thank you very much for that offer. I've pared down my code to a simplified version that exhibits this behavior. The only step is to build and create a new document. I can send the compressed project folder to you. Where/how should I send?