Now that my current release is a few weeks in, I'm seeing some interesting stats for the previous one.
Old Magic was a change in genre for me, from Space Opera/Fantasy based, to Contemporary Fantasy in an urban setting. One of my main characters does an extended cameo, so it's firmly in universe.
The launch totally flopped. Definitely the worst launch for a long time.
Several reasons though, including the change in genre, and the cover being wrong as far is being in universe is concerned. It's also a stand alone.
BUT....
Well into the cycle of the next release, the 90 days stats are showing me a different story.
While sales are down, KU full reads are significantly higher, with the money being about normal.
In fact, the only reason why this book is not performing much better than previous ones in money terms is it's a lot shorter than my normal, and only just novel length for the same price as my books averaging 12k longer.
So, far from being a flop, it has in fact performed very well, even though it gained no decent rank.
It is however holding rank quite nicely, when normally it would be sinking rapidly by now. Part of that though is the last release references the main character from Old Magic, 600 odd years in the future, and so some of my normal readers who ignored it have been going back to it.
One of the things I keep telling people on Quora answers is initial sales are not the be all and end all.
It's how the book performs in the long run that counts, and potentially, the long run is now possibly decades if you can keep your momentum going.
My first book, now 7 years old, is still hovering around the 50k mark. My book 2 is still at the top of my all time sales totals list, in spite of my series 3 books which hit #132, #97, and #218 respectively.
It just goes to show that you can't judge a book by it's initial performance.