Sometimes, after i successfully hold the call through Jizzy (cutscene) (can be sure, cause i notice quickly changing on_mission from 0 to 1 and then back to 0 after skipping the cutscene), and then try to let go at the start of the cutscene at Jizzy's, interior will disappear, and after skipping the cutscene, on_mission will change to 1. But other times, when i'm doing exactly the same, it's going smoothly afterwards. What's the problem?

"Interior disappears" That is the usual mini cutscene that plays just before a mission starts, with CJ walking towards the door/building of the mission vendor, the mission name on screen, and the screen fading. The difference is that the outside world is invisible (the game only shows one interior at a time, in this case Jizzy's one; the outside world is "interior 0") so that you just see grey around CJ. Put simply, you accidentally duped the mission.

That happens if you drop the call while inside the cutscene interior.

Make sure to either

1. keep holding the call button or

2. drop the call button before the mission starts (in this mini-cutscene I described but with the outside world visible this time ;)).

3. is faster if you want the call to count as taken (for that you have to wait for the conversation to start before pressing F). In 1), the game drops the call button for you the moment you skip the cutscene.