Version 1.67.4, code 276 (it would be nice if press-holding this in the settings would copy this info to the clipboard, by the way)

1. See this comment
2. Reply to it
3. My comment appears with the rest of the top-level comments with no color banner spanning the left side, and not directly under the target comment
4. Retry steps 2-3, twice, with no change
5. Delete comments and finally refresh the whole thing and then see them get reorganized and receive color banners

Wut. This has never happened before.