I experienced the same thing, except 404page plugin is not installed and the activated theme is OnePress not Gabfire Stylebook. The last update to my WordPress install was 1/22/18 – to: Version 1.7.3 ( WP Version 4.9.4 ).
I published a page on 2/6/18. This was the first Page published since the update installation, but also the first Page published in over two months. Over 1,300 Pages were created along with the Page I intended to Publish. All the ‘(no title)’ Pages were dated within seconds (up to minutes due to volume) of the last valid published Page.
The last plugin installed was Reusable Text Blocks on 2/1/18, and does not create Pages but rather Posts. The Page I published does not use the Plugin shortcodes either. Since we don’t have the same plugins or theme, I’m thinking this is not related to a specific theme or plugin…
I tried to recreate today (2/8/18) but could not. I tried doing a draft, then publishing, straight up publishing, creating a post then a page, editing a Page and Post with the RTB shortcodes and publishing – and have not seen any ‘no title’ Pages created. I did not install any new plugins or themes and try those steps since I’m not an admin.
Other (maybe) relevant information: Using Project Nami and on a SQL database.
