A dogged photo-journalist who is one of seven witnesses to the death of a young woman gradually exposes the thin veneers of the six other people interwoven in the dead woman’s life and the powerful man that killed her.

What does exposing look like? What does exposing mean? Expose to whom? Will he or she publish stories in newspapers? In magazines? Online? Will he or she shoot a documentary about the killing? Investigate and report to the police? Etc...

Because the list of options is long "exposing" becomes too vague to describe a specific goal and action which means the logline doesn't describe a main action the MC will take or specific goal he or she will pursue.

If the inciting incident is the death of the young woman the logline needs to specify it as such i.e:
After the death of a young woman the main character must...

Journalists see many atrocities over their career even if this one hadn't prior to this event why does he or she need to find the killer? It isn't their job and there are no personal stakes for them in the murder how is this crime different to the many others for him or her.

Lastly the six other whiteness of the crime seam unrelated to the story, how do these characters progress the plot? How will they present an obstacle for the MC to over come?
Currently the logline could do with out them.

You say it lacks causal connection b/w I.I and MC action, but if fact there is one: the journo witnesses the death and the action is exposing the man that killed her.

Colourful descriptions such as "...dogged photo-journalist?" and "...thin veneers ?" and "...interwoven in the dead woman's life?" are vague in nature and do not contribute to a clear understanding of the story.

Best to specific the inciting incident in a clear and concise manner for example: After a journalist witnesses a murder?

A big problem in this logline is the lack of a causal connection between the inciting incident and the action the MC will take. Why must he expose information about these other people after witnessing a murder?

Lastly and most importantly what is the MC's goal? Gradually exposing is the action the MC will take but to what end? Also not sure that a gradual exposition of other characters would make for a compelling act 2? Is there anything else he or she can do?

Hope this helps.