Just today (so presumably related to today’s patch), both Special Delivery and Potion of Sparkling are bugged in Duels.
Special Delivery appears to only be triggering on the first rush minion played each turn.
Potion of Sparkling is inconsistently triggering only on one of the adjacent minions. I think it may be that it only triggers on minions to the left of the attacked minion (not 100% sure), but it is definitely not hitting both adjacent minions.
Same thing happened to me with special delivery.
Nevermind, I should have read the patch notes more carefully. These are operating as “intended” now.
I get only the graphics effect and no damage from Potion of Sparkling.
Same as of an hour ago. Yes to animation, no to output damage.
Same here, today, for the Potion of Sparkling that does no damage. It’s not very funny to play with a useless passive on a heroic run 
…
Just echoing what others have said - only animation, no damage! 
Same issue, tested in heroic duel on iphone. Hard to play a rush build in these conditions.
In game potion of sparking didnt work, the effect had animation but nothing took damage. Sadly that ended my heroic duels run.
Same here! Only animation, no damage…
I also had this issue and as a result lost my last two games. I had waited between the two games, assuming the bug would be fixed. Can we get a free ticket in compensation please.