I have had your exact same problem or something very close. firstly one thing I remember is when you finish the processing, the whole mesh disappears for some reason. this is easily fixed by simply clicking on the eye icon to hide and then click again to unhide.
as for making the mesh into a successful surface..... this can be a very long process. I have found using mesh mixer can be pretty handy. you can clean up your model before importing.
there is also a slider bar in the surface wizard allowing you to increase or decrease the detail. experiment with this to see if it helps. Sadly the model can become useless after processing but pre processing before import can be a lifesaver.
Mesh mixer is freely available and reasonably straight forward to use.
maybe not much help but hopefully gives you a bit of direction...
Thank you for your reply! The eye icon does help, odd that I need to click it twice before it works.
Mesh mixer is useful tool, thanks for recommending. Still having the same issue but I was able to at least 3D print after cleaning up the model.