My railings looked good until I decided to follow along and click “Remove Doubles”, I must’ve done something funky with my model since this is what happens :
Before
After
My railings looked good until I decided to follow along and click “Remove Doubles”, I must’ve done something funky with my model since this is what happens :
Before
That looks like an overzealous Merge Distance when you do your removal. Try it again and check what the merge distance is set to in your operator panel on the lower left - if it’s anything higher than a really low number it’ll start devouring the mesh willy-nilly like you’re seeing there.
I keep mine set all the way down to zero, since I’m snapping to grids, edges, etc., a lot, so when things are overlapping they’re precisely overlapping. If I wanted a bit of wiggle room it would still be set very low, like 0.001 or less.