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does anybody run into this problem when trying to finish form.
not sure what exactly to repair
This is the Inventor Fusion for Mac forum.
You want the Fusion 360 forum.
To answer your question you have created a T-Spline body that is not able to be converted to a solid body which is what happens when you finish Form.
This means there are likely overlapping shapes that prevent a clean conversion. If you haven't already please re-post and perhaps include a picture or two of your model in the Fusion 360 forum so experts and users can help you.
Also, in Form, there is a tool called Repair Body that may help. Look on the modify menu.
I hope this helps.