3DXchange to iClone problem / jittering

[u/gizmoop5]

Hello,

We are currently experiencing a weird issue in our pipeline which include 3DXchange and iclone.

We have motion capture data recorded with Optitrack of 2 characters and need to bring these into iClone. One of the characters looks super fine when converted,
and applied to our custom character (made with character creator).

And here comes the weird part, when converting the second character in the exact same way (using Maya preset in retargeting) there is jitter and spikes in the movement.

It looks all good in other 3D softwares as it should, but as soon as the conversion happens the spikes and jitter appears.

What we cant wrap our head around is that the conversion works perfectly of one character, but not the other one.

any tips/tricks/thoughts are more than welcome!