IAP, Google Play, Android, Promotion - cannot get rid of transaction

I created promotions via Google Play. I have Consumable items. I used 1 promotion in Google Play. I started the game and had an exception message (something like 'recorded transaction'). I cannot buy the same item again, and the transaction record doesn't go anywhere. I can see the product's transactionID as well.

I updated IAP package to 2.2.2. I reinstalled the game with more logs. I uploaded my apk to the internal testing track and got it from there. When I launch an app, the shop calls ProcessPurchase method of my store manager. I always return 'Complete'. I watch logs via LogCat and nothing exceptional is going on (no errors, or abnormal behavior). And yet... I still have this transaction. I tried to deal with it with ConfirmPendingPurchase, or deactivating the whole promo action, yet it appears every time.

I need to get rid of this transaction, but Unity's IAP doesn't provide such functionality. This transaction doesn't allow me to purchase the item normally anymore (throws duplicate item, and error in UI). It seems that I ran out of options on how to accept/clear/decline this transaction that was made in Google Play via promo code. Please, help!

 

I have only consumable items. The item is consumable.