We have one task with multiple comments. For some comments there is a "Quote" option in the dropdown menu, and for some there are only "edit" and "delete" options.
The "unquotable" comments are all one after another, from the beginning of the thread. The Rest of the comments are "quotable"
This appears to affect comments which are initially hidden, then pulled in by Ajax. Likely related to T4712.
I seem to be able to reproduce by:
(This might also have been preexisting, I'm not sure it worked before T4712 -- I probably never tested it when writing the original stuff.)
I did a pretty big update yesterday. I am quite sure (not 100% though) that it worked before.
I'll take a look at this, but this part of the code is mysterious-ish to me... (It also gates "View Raw" and we have an issue with these things not showing up for logged out users?) I'll minimally surface the details of the mystery.