From the Known issues for patch 26.4,
[Resolved 6/15] We’re aware that ongoing Duels runs did not retire with the patch. Instead, the season reset will happen when players finish the run on their own (either by retiring or playing all their games). Players who had an active that would have been retired with the Patch 26.4 reset will be granted one Tavern Ticket in an update soon.
While this issue is marked as resolved 6/15, as of today I still haven’t received the ticket on either my America or Asia account.