This problem seems to happen when the search query (that triggers Quick Answer by ending with '?') is long.
Writing a followup question does not send you to the thread page containing the initial query and the follow up, but instead, sends you to a 404 page.
Here is a specific real example:
Search query: generic term for (typically) rubber material thing that connects rotary motion of one part of the car engine with other parts?
After submitting the followup question, we get a 404 and a defunct URL:
Even if I check my assistant.kagi.com Threads, it is not there either.
―
I expect it to work normally as expected.
