Unions not working properly?

Hello! I am new to the forum so I hope I am making my issue clear enough.

What am I attempting to achieve? I am trying to simply union like I used to without issues.

What is the issue? When I try to negate unions which I believe were made with CSG Legacy where before it worked fine however now it does not (CSG Legacy) and says basically that the union is unsolvable when I try to negate it, though its worked many times before. CSG Legacy (on the left) is also the original model, so that’s how it should look, however I can’t negate it.

What solutions have you tried so far? I basically turned off CSG Legacy and enabled CSG V3, this worked but to an extent for the visor obviously has some unwanted lines, I have put together and image to show examples of my problem.

Again sorry if I am not being clear enough, thank you!

You could try deactivating CSG V3, but solid modeling is not a reliable method for creating meshes, of course its possible to do it, but it would be way easier and faster to make your model in any 3d modeling software, like blender.

Roblox staff have stated that:

and this might be the issue you are running into, but there’s no real way to be sure. I suggest you post a reply on this post with your issue and provide a file with the union so they can take a look and maybe help you fix it.

I hope this helped.
Good luck.

Thank you, I will make sure to ask them about it.