Hi there, thank you for purchasing the mega pack bundle!
Regarding the issue with frames 11 through 15 getting cut off, I suspect this is due to a DPI difference between the game engines. The kit was originally created based on Unity's standard of 72dpi. Because Unreal Engine uses 96dpi, the animation frames might be rendering larger than intended, causing the image area to go out of bounds and appear cut off at the top. Also, for your reference when setting up the flipbook, the animation is designed to run at 60fps (UMG FrameInterval: 0.0167).
I am going to look into this right now to verify if this is the exact cause. I will check the files and get back to you with a fix or an update as soon as possible.
I apologize for the inconvenience this has caused to your project, and I really appreciate you letting me know about it!