Hi falviani, welcome here.
First notice that one of the bodies is in Display Mode = Tip which will prevent sketch editing. You have to turn is back to Through.
Also in your Sketch, there is something like a null-length line as complained by FC in the report view. The element "16-Line" is the culprit and can be simply removed.
Beyond what was already said, indeed your model seems to be a bit 'messy'.
Fusion001 fuses Fusion with items that are already contains in Fusion itself, which not really has a sense.
Also each fusion has a double reference to the body. One is correct (to the body itself) but the other is not (to the pad that is inside the body).
All in all your file can be simplified to the one attached.