... is possibly connected to this one: https://forum.beta.forgeofempires.com/index.php?threads/tavern-sign-timer-broken.10656/
I just popped on to see if this had been reported yet. I too share this issue with the ADAntiques Dealer shows absolutely wrong time to the end of both deals that don't expire.
P.S. It actually shows the time of the tavern boost. xD