Hi!
I'm creating skins for a series of animated projectiles, of which I've made about 15 without issue. Each skin features a sequence of images. Suddenly, upon creating my 16th-ish projectile skin, I'm unable to key the image sequence into an animation.

Details:
I've been animating a series of projectiles in one large Spine file. The way this works is that I made 3 base animations for a generic projectile, then used skins to replace the images, creating a variety of visually distinct projectiles. Each projectile consists of a sequence of images that I key into the beginnings of the animations. Despite using the same animations for most of the projectiles, I find that I need to re-key these sequences every time I make a new projectile skin. Now, to the problem: for some reason, when I added a new projectile skin, this time when I went to re-key the sequence, I was unable to.

What I tried:
I am unable to key this particular sequence into any animation, including brand new animations I created to test this issue. When I click the key button next to the sequence, it just stays green (whereas it usually turns red).

I'm able to copy and paste existing keys of the sequence into new animations, but if I try to edit the sequence by changing the frame it starts on, the key button turns orange and then doesn't save that change.

I tested other, pre-existing skins, and I'm still unable to key the sequence. I am able to key other sequences in the project -- ones on different meshes/slots/bones, but this projectile sequence specifically is unkeyable.

So, have I hit some kind of limit on the number of times a sequence can be keyed in one Spine file, or am I missing something here?

Using 4.1.23 PRO, launcher: 4.1.11