Quests are missing

[езже]

after talking to the fixer and the weapons seller and someone else, the quests just disappeared

[Elondre]

Yes because the quests are a tutorial and you are done with the tutorial

[Urban Blackbear]

It can happen when you don't meet the requirements for the next progression flag. Usually a required xp rank or unlocking a supplier.

[Rini]

as urban said, might not meet the requirements for next task, or you could have hidden the task in your journal (key "J") by clicking on it.