Pokémon GO developer Niantic has confirmed the widespread Friendship Level issues that have been affecting a number of players across the globe. The developer is working on dispatching a permanent fix and has provided a temporary workaround in the meantime:
Friendship Levels may not increase once per day
We’re aware of an issue where Friendship Levels become out of sync between two Friends and progress may not increase once per day as intended. Trainers affected by this issue may complete an activity with their Friend but their Friendship Levels may not increase for one or both Trainers. This issue is more likely to occur if the Friends are in different time zones from one another.
We are actively working on a resolution to this issue.
Workaround:
It may take multiple Friendship activities for your Friendship Levels to increase. If you notice that your Friendship Level has not increased for the day after participating in Gym Battles/Raids, trading Pokémon, or sending a Gift to your friend, please complete another one of these activities with them.
Source: Official Pokémon GO support page
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