Help with layer masks

Hey guys. First of all, thanks for sharing all your hard work with us, it's pretty fun putting krystal in all these naughty poses.
I gotta hand it to you guys, I must've wasted 10+ hours just on this so far lol.
But uh, I'm trying to set up a scene with krystal eventually getting DPed by two sharpclaw. I got one set up with masks to actually look like penetration. Only problem is, when I export it, my layer mask, for all intents and purposes, seems to disappear completely. Works perfectly inside the flash window though, as shown in the screenshot below. Any thoughts?

But uh, I'm trying to set up a scene with krystal eventually getting DPed by two sharpclaw. I got one set up with masks to actually look like penetration. Only problem is, when I export it, my layer mask, for all intents and purposes, seems to disappear completely. Works perfectly inside the flash window though, as shown in the screenshot below. Any thoughts?