Leaving gaps in solid parts

[Stunts 0]

I've tried reorienting this print several times. I'm relatively new to 3d printing but Cura has been the slicer I've spent the most time with and become mostly comfortable with, but I take the same model into slic3r and it comes out fine. The spikes of the shield don't seem to actually be attached every time I've sliced it. I have tried changing multiple settings. I'm not sure what else to try to fix this.

Goblinmelee_2mm.gcode Goblin melee NEW.stl

[Stunts 0]

I did manage to get it to work by using the meshmixer make solid function finally, but it does seem like it should work fine without that since it works in slic3r just fine.

[burtoogle 515]

Firstly, the model does have some problems as reported by Cura's mesh tools plugin (get that from the marketplace).

 

 

But it did go on to slice and, for me, the spikes are attached to the shield...