I'm so confused. Did Sensei really dust off chapter 188, and use it as the first chapter of a new volume?
It's because chapters published separate of the volumes are numbered differently from the chapters placed in the volumes. In the volumes, a number of chapters are combined so the count is different in the volumes and out of them. This isn't a new chapter for a new volume, it is just the magazine published version of the same chapter from Volume 17. It's kind of confusing, I know.
And it will continue to cause confusion going forward, since these chapters will vanish and be replaced by the actual Volume 18 chapters in time, causing further confusion with the chapter comments being tied to the wrong volume chapter.
Fun!