Marvel's Midnight Suns explains some things very well but some key details are sometimes left out.
There are, however, some things that are not explained that well, like one rather important part of the friendship system.
Whenever you fill the friendship bar with a hero, the friendship is supposed to level up but sometimes you can end up having one or two of them with a status of "Friendship level up pending" which could worry the player. The good news is that there is nothing to worry about.
Friendship level-up happens when you get a private message on the Superlink from the hero that you filled the bar with.
The log of friendly activities in the Abbey sometimes just gets too cluttered for the Hunter and the game needs to queue them up. On rare occasions, the friendship level up will take a backseat to other activities so you will just need to deal with the other activities first.
Sometimes this might mean you will need to wait until the next day to level it up but in general, it shouldn't be an issue.