Might help - you sort your problems,
I am happy to help out, but Chris and I have not picked up your design intent.
I found the actual problem with the Section Analysis, you have symmetric? cavities in the model.
some things to consider -
build your body on one side of the origin plane, when done mirror it.
creates half the work.
Use eyeballs to hide stuff, what gives with the split body move?
It can just be left where it was and hidden with the eyeball.
Do not use the Move Tool.
Fully define sketches.
Remove empty sketches.
Too many spline points.
I have forgotten where the origin was, but after the move it was no further use to you.
You have a sliver body so small it can not be seen in the window, but earlier in the construction you were Extrude cutting them out of existence,
where the body > Remove would save a few sketch / Extrude manoeuvres,
two sketch / extrudes that might be symmetrical, in separate sketch extrudes.
Use oversize Sketches to cut or add material, so that these sliver cavities will not be there.
And these Might help....
