Load up the Intermediate_OnkbaAWDAnimation in the 4.1 dev examples.
Press E key to punch and keyup before the punch finishes.

Do that a few times and the character will sink into the ground.

Im guessing thats to do with the CrossfadeTransition.

So how do we get round the issue?

To add on to this.

Setting the animation node to not loop
eg
animationNode.looping = false;

press and hold the E key to punch.

At the end of the punch the character begins to sink while the E key is pressed.

Hello john

Its probably something to do with applyPositionDelta.
Which you can turn off but then you animation is suck at the origin.
Bit like how you see it in prefab.

The hack is (redo all your lovely animation)

Use a skeleton that has a root bone thats located on the origin throughtout the animation and you use the next bone to animate the whole body. Then you dont get the issues.

edit…
Just parent your skeleton animation to a bone placed at the origin and export.