No. I mean try to animate the mannequin using its default animations.
Okay, one of two things (or both) is going on:
- Your animation that you created is no good.
AND/OR
- Your coding is incorrect.
There already seem to be issues with your animation, itself, so animate the UE4/UE5 MANNEQUIN using its DEFAULT ANIMATIONS. NOT YOURS.
If you can successfully animate it, it means your code works, and your animation created in Blender is the issue.
If you cannot animate the mannequin properly with its own animations, then you need to practice more / look up a tutorial on how to correctly animate simple actors.