Hi Simon Corompt, on Slack, this is likely the result of how retrieval happens on Dust.
Essentially: we group messages together in 'chunks', and then get the most relevant chunks for the query.
if the message is in a thread, then the thread will be its own 'chunk' of text and the reference will be correct.
if the message is not in a thread, it's likely to be grouped with other messages. The citation therefore links towards one of the messages from the group, but not that specific one.
It's a known friction and we will likely improve it in the future. The good news is that the citation still corresponds to a piece of text that was relevant.
hope this helps