Is your animation moving when you create a new one?
I have found that when I am previewing my animations, I can't toggle to another animation that has either 0 keyframes or only keyframes on frame 0. I can only toggle to ones that have multiple keyframes along the timeline. Spine crashes if I try to toggle to one with either 0 keyframes or only keyframes on frame 0. That's why if your animation is previewing and you try and create a new one, it crashes since there are no existing keyframes.
I also get a crash when I re-click on the toggle button of the active animation while it is previewing. If I re-click it while it is not previewing, it just toggles off the animation and the skeleton goes back into setup pose without the ability to create keyframes, since no animation is selected.