X comics are getting cancelled almost as fast as bad series in Shonen Jump lately. The hard reality is for most of these series is that the sales just aren't there. If its not selling, its getting the axe. In this case Leah is almost lucky that they thought she had a good enough story idea to give her an entire miniseries after her main series ended.
As for why so many are failing to catch on, its really hard to say. CotA and X corp are just not good. And I think a lot of fans on here and early writers drastically overestimated the 'mystery' of how the island of Krakoa works. So many of these stories feel like they were suggested based on worldbuilding prompts, and the story built around those prompts just wasn't interesting enough to justify making an entire book about them. Worst for me was that we were promised the truths and details about the resurrections, and the only one we really got was that they will forcibly bring back people who don't want to be brought back.
That's a whole different issue for me. Whenever we get these worldbuilding reveals it always feels like its just made everything look more scummy and just makes it harder to care about any of these people.