Have you tried to re-access the attributedText without using the DispatchQueue? I have some similar problems with UITextView.
Kable
Users receive reputation points by contributing quality content to the forums.
Posts include post and replies published on the forums.
Post authors can mark replies as Accepted to indicate successful solutions.
Apple Developer Forums admins can mark replies as Apple Recommended to indicate an approved solution
Post
Replies
Boosts
Views
Activity
I've got a similar problem. It seems that AVSpeechSynthesizer does not work well with Address Sanitizer. I spent a lot of time trying to figure this out. Terrible experience! Don't want to believe that the Apple engineering team left this problem unsolved for a year. For a temporary solution, can they just turn off the Address Sanitizer for AVSpeechSynthesizer?