Mobile Bug: Black Box instead of Animation

I have a weird bug that sometimes my characters walking animation sometimes jumping animation is replaced with a black box. I don't know how to avoid this. Can you please help me ? Thanks.

It's indicative of an animation that's too large to fit within a 1024 wide animation strip. We're working on a workaround to this limitation, but shortening the animation of chaining multiple animations together will get you around the issue.

I have a weird bug that sometimes my characters walking animation sometimes jumping animation is replaced with a black box. I don't know how to avoid this. Can you please help me ? Thanks.

Same issue, but small animation, and only see it on Samsung so far.
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