Inconsolata and some other fonts may be missing from the default list of the monospaced fonts available for the editor.
Inconsolata family contains only one font style — plain. When bold variant is requested to be rendered, IDE will derive a synthetic bold version of the font, which will not have the same width as the original font. As a result, if a file contains both plain and bold text, font will not effectively be monospaced.
That's why Inconsolata is not listed as a monospaced font. You can still use if if you wish, but if you want to preserve its monospaced property you'll need to use a color scheme in editor which doesn't use bold font at all (default one does). The logic for emboldening a font is implemented in FreeType library, it's not easy to change it.