The profile should now extrude fine.
Very rarely do I use Mirror tool in Sketch environment.
If you count the number of mouse clicks I will wager my technique was fewer clicks that that on the YouTube video.
In any case, Inventor often has trouble combining coincident points when using Mirror.
If I need a Symmetry constraint - I will add it myself rather than doing Mirror.
If we assume (which I think is a safe assumption) that the design intent was really for those arcs to be tangent - the curve is just slightly different.
(both curves shown)
Mm.. I would have expected a "thank you" or similar sort of reply to your posting from him..
Anyway, I hope you'll still read this old thread..
How did you make that arc feature tangent to the the filet?
Did that depend on where you put the first 2 points of the arc?
Or did you constrain that?
Click the points for the arc anywhere except for the endpoints of the existing arcs.
Then add the Tangents yourself.