See the attached screenshots. The markup seems correct, but somehow the ) is gone in Summit.
Original markup:
Bonus panel
Edit: Actually, re-checking my post, I can see even in the code block that the bracket is gone, please use a browser to check the actual source.
Test:
the quick brown fox jumps over the lazy dog
spoiler
the quick brown fox jumps over the lazy dogIs it specifically eating brackets, or just whatever the final character is?
The last character