This is a Terrible DXF.
3837 pieces of sketch geometry many many open gaps, double line, it has all the issues a bad DXF can have.
This is how I would go about “fixing” this
Starting with the imported DXF in the sketch environment
Finish Sketch and double click your center mouse button so the image fills the whole screen.
Capture Image ( We capture the image in the design workspace so the constrains and point are not visable)
Open 3D paint in windows and open the capture image and fill the area with black.
Now resave the image
open https://convertio.co/ in your browser and open this image and convert it to a SVG.
Download the new SVG
Open Fusion 360 and insert the new SVG into a Sketch. unlock it !
Now there is only 1324 pieces of geometry and all the contours are closed.
you could still replace the mounting holes with round circles at this point if you wanted.
It now works well in fusion 360
