Pokemon GO players have come across a new bug that causes Trainers not to receive double experience for Friendship level increases while using a Lucky Egg, Niantic stated on their blog. However, the problem is not the Lucky Egg, it is the delay in notifications. Niantic has made the title a bit misleading, making players believe that the issue is in the Lucky Egg.
In normal circumstances, when you level up your friendship level, a notification on your screen should come right up but in this case, it comes after some time when the effect of the Lucky Egg has finished, resulting in getting a regular amount of XP instead of double XP.
As per Niantic:
When using a Lucky Egg, Trainers do not receive doubled experience as their Friendship levels increase.
Issue description: Trainers may see a delayed notification after the effects of the Lucky Egg have run out, causing them to not obtain doubled experience for their Friendship level increases.
Issue status: Investigating
It seems that there is a broader bug in the game that causes notifications to come with a delay for each task, action, and catch that you complete. There are many records of this bug, so we advise Niantic to fix it as soon as possible because many players are losing XP.
Have you come across this bug?