SophieKSP

I solved the problem, turns out that somehow my game was accessing the wrong fuel tanks in the story mode, the old ones from before some update. So I uninstalled the game through steam and then deleted all files for KSP in steamapps/common. On a fresh reinstall the fuel tanks were different looking to the old ones but unlocked in the same way and worked without issue. Issue resolved. Thanks

I forgot to mention that I did try both of those, and I do get file errors when I verify it. I tried verifying, opening the game and not doing the bug, then verifying again and I got one file error. Uninstalling reinstalling doesn't seem to help either. I discovered a weird trick where I can reset the craft design by clicking the new button, which works even after the bug happens. Then if I start my craft with a fuel tank piece then it appears fine and I can attach more modules to it and it seems to work, but any further fuel pieces will get the bug again. If I try radial fuel pieces then bug happens but the other parts of the radial fuel pieces do not vanish, but also cannot be touched.

I am playing story mode on normal and for what I can tell I cannot seem to add fuel tanks to my spacecraft without it breaking. When I attach a fuel tank as normal to any part of my craft the fuel tank then disappears and from then on the game is bugged in this mode and I need to force quit it. I cannot exit out of the builder but have to close the game entirely. It only has happened for fuel tanks but it is all fuel tanks that I attach to any other part of the craft. Rocket boosters attach and work as normal, engines can attach without breaking, but obviously without fuel. It's only fuel tanks. While the game is bugged I cannot attach anything more to the craft and sometimes I cant even remove the thing I attached the disappearing fuel tank to. Any fixes for this bug, or any more info needed?