Niantic aware of Friendship Levels issue in Pokemon GO, working on a fix

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.