After three teammates are killed in separate incidents during a mission, an elite surveillance operator struggles with being labelled as a magnet of doom by a fellow operator simply because all three men were in close contact with him just before they died.

To help with the above comments you need to increase the stakes. Try changing "...struggles with being labelled..." to; is accused of murder or is put to a court-martial.
In loglines the verb struggling as the main action for the protagonist is often a weak description of what they will do because it is vague and doesn't paint a clear image of what the story will look like.

Also I'm not sure what "...an elite surveillance operator..." is can you describe the protagonist in a more succinct and clear manner?

Hope this helps.

You need a plot. That will greatly improve this logline.

The protagonist is passive -- reacting to what other people think of him. What is he doing about it? What is his objective goal? Who/what opposes him? What's at stake that the audience should care what? It's got be something more than what his fellow operators think about him.