Also note that a UID range of 559:* always includes the UID of the last message in the mailbox, even if 559 is higher than any assigned UID value. This is because the contents of a range are independent of the order of the range endpoints. Thus, any UID range with * as one of the endpoints indicates at least one message (the message with the highest numbered UID), unless the mailbox is empty.
So if the highest UID is 100014, and Thunderbird requests
174211265:*, that request is equivalent to
A non-existent unique identifier is ignored without any error message generated. Thus, it is possible for a UID FETCH command to return an OK without any data or a UID COPY or UID STORE to return an OK without performing any operations.
So the correct response would be to return only message 100014.
Though it seems rather suspicious that Thunderbird would just make up that UID number, so I'd double-check the traffic between the client and the server to ensure that the server isn't sending incorrect data.