Maya 2018 Booleaan and Target Weld causes mesh to disappear?

Amank679

Hi all,

I'm working on a gun model and am trying to boolean a certain part. For whatever reason, when I boolean, the mesh vanishes. I have to undo and re-boolean several times in order for it to work. 

Also, When I'm cleaning up a model with target welding, the asset disappears again.I've reset both tools multiple times and switched to legacy versions but to no success.

I'm not quite sure what's going on. I'm using Autodesk Maya 2018 and it's the latest version. 

Please let me know your thoughts.

Thanks in advance!